Ayhan F and Konopka G. Genomics of autism spectrum disorder: approach to therapy [version 1; peer review: 3 approved]. F1000Research 2018, 7(F1000 Faculty Rev):627 (https://doi.org/10.12688/f1000research.13865.1)
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Autism spectrum disorder (ASD) is a highly prevalent neurodevelopmental condition with no current treatment available. Although advances in genetics and genomics have identified hundreds of genes associated with ASD, very little is known about the pathophysiology of ASD and the functional contribution of specific genes to ASD phenotypes. Improved understanding of the biological function of ASD-associated genes and how this heterogeneous group of genetic variants leads to the disease is needed in order to develop therapeutic strategies. Here, we review the current state of ASD research related to gene discovery and examples of emerging molecular mechanisms (protein translation and alternative splicing). In addition, we discuss how patient-derived three-dimensional brain organoids might provide an opportunity to model specific genetic variants in order to define molecular and cellular defects that could be amenable for developing and screening personalized therapies related to ASD.
Corresponding author:
Genevieve Konopka
Competing interests:
No competing interests were disclosed.
Grant information:
This work is supported by grants from the National Institutes of Health (R01DC014702 and R01MH102603 to GK and T32DA007290-24 to FA), the Simons Foundation Autism Research Initiative (project 401220 to GK), and a James S. McDonnell Foundation 21st Century Science Initiative in Understanding Human Cognition – Scholar Award to GK.
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Autism spectrum disorder (ASD) is a phenotypically and genetically heterogeneous neurodevelopmental condition that manifests as deficits in reciprocal social interaction, repetitive behavior patterns, and restricted interests1. The prevalence of ASD is as high as 1 in 68 children2 in the US, and ASD has a profound impact at the individual, family, and societal levels. Although environmental factors likely play some role in the etiology of ASD3, family and twin studies show that genetics contribute to the majority of the risk associated with ASD4–9. Genome-wide studies using genotyping microarrays, whole exome sequencing (WES), and whole genome sequencing have identified a rapidly growing number of genes linked to ASD10–21, providing a window into the molecular underpinnings of the disorder. However, our understanding of molecular mechanisms anchored to this heterogeneous group of genetic variants is not entirely clear. The paucity of disease-modifying therapies or molecular diagnostic tools for ASD makes identifying molecular disease mechanisms critical to assist developing rationally designed therapies. Additionally, details regarding the time course of molecular alterations in ASD can inform diagnostic biomarkers and quantitative measures to indicate disease severity and evaluate the efficacy of future therapeutic approaches.
Here, we review the recent progress in understanding the underlying genetics of ASD, including the identification of inherited, de novo, and somatic mutations linked to the disease. We then discuss how convergent disease mechanisms in ASD can potentially translate into the most appropriate biomarker development and treatment strategies for individuals or subtypes (or both) with ASD. Finally, we consider the unprecedented premise of patient-derived three-dimensional (3D) brain organoids as appropriate models to test and validate the functional impact of identified genetic variants as accessible and flexible platforms to screen and test for therapeutic agents.
The complex genetic makeup of autism spectrum disorder
The importance of heritable genetic variability in ASD pathogenesis has been highlighted in twin and family studies. The increased prevalence of the disease in siblings of ASD patients and greater ASD concordance rates in monozygotic twins compared with dizygotic twins has prompted significant efforts toward understanding the genetic architecture of ASD pathophysiology. Although the identification of mutations linked to monogenic syndromic forms of ASD, including Fragile X22, Rett23, MECP2 duplication24, tuberous sclerosis complex25, PTEN macrocephaly26, and Timothy27 syndromes, provided key insights into the genetic basis of ASD, these rare syndromes collectively account for only about 5% of ASD cases28, leaving the etiology of non-syndromic ASD cases mostly unknown. The highly heterogeneous disease presentation of non-syndromic ASD initially posed serious impediments for identifying reproducible ASD-associated mutations. Despite these challenges, the assembly of large patient cohorts along with advances in genomic technologies within the last decade has facilitated the identification of ASD-associated variants in hundreds of genes, including single-nucleotide variant (SNVs) and copy number variants (CNVs)29. The use of WES and whole genome sequencing in family cohorts with sporadic ASD (simplex) and with more than one affected individual (multiplex) led to the discovery of both rare inherited and de novo ASD risk variants. Rare recessive mutations have been reported in genes such as CNTNAP230, SLC9A931, AMT20, PEX720, CC2D1A32, and BCKDK33 in consanguineous families with ASD and epilepsy, highlighting the role of recessive inheritance of deleterious mutations associated with ASD. The role of inherited variants in ASD was further supported through WES in larger cohorts of unrelated families34,35. WES in large cohorts of simplex families (one affected child sequenced together with unaffected parents) provided substantial insight into the role of de novo (or spontaneous) genetic variants in ASD. Numerous studies have reported increased rates of rare de novo CNVs and SNVs in individuals with ASD10,16–18,36 and have identified high-confidence ASD genes, including CHD816,18,37–39, SYNGAP121,40,41, DYRK1A42, and SCN2A16. Moreover, targeted sequencing approaches confirmed the recurrence of some of these de novo mutations in independent cohorts, substantiating their role in ASD pathogenesis10,36,39. Finally, one very interesting group of genetic variants that has recently been implicated in ASD is somatic mutations43–45. Somatic mutations can occur during development and yield mosaic individuals with distinct cellular genomes in subsets of their somatic cells46. Whereas routine genetic sampling from blood misses the disease-associated somatic variants in the brain, targeted sequencing on ASD post-mortem tissue has detected increased rates of deleterious somatic mutations in cases compared with controls45. Interestingly, there may be some overlap of genes at risk for both germline and de novo somatic mutations (for example, SCN2A)43. Future single-cell sequencing approaches47 will be informative to identify and characterize cells that carry disease-related somatic mutations48.
Taken together, recent advances in ASD gene discovery highlight the complexity of the genetic landscape of the disease while beginning to shed light on some of the biological pathways at risk in ASD. This complexity is underscored by the potential for certain combinations of common genetic variants contributing to ASD by increasing an individual’s susceptibility to pathogenic effects of rare inherited, de novo, or somatic mutations. Given the progress in identifying high-confidence risk genes for ASD, investigators can now direct their attention to understanding the pathogenicity of this genetic variance and identifying potential common convergent disease mechanisms as molecular targets for future treatment strategies.
Convergent molecular mechanisms
One approach to understand pathogenesis and identify therapeutic targets amid a complex genetic architecture is to elucidate downstream pathways commonly affected across ASD cases with distinct genetic etiologies. One example of a convergent molecular mechanism includes defects in the regulation of protein synthesis and alternative splicing (AS) as potential unifying pathways for ASD49.
Precise regulation of translation at synapses during the tight window of a learning experience has been shown to be extremely critical for the formation and maintenance of long-term memory50. Several mutations in translation factors and regulators such as eIF4E51,52, TSC1/253, and PTEN54 are associated with ASD, underscoring the involvement of translational defects in ASD pathogenesis. Furthermore, there is emerging evidence showing dysregulated translational activity in cells derived from non-syndromic ASD patients, including aberrant activity of mammalian target of rapamycin (mTOR), a key regulator of translation, suggesting translational dysregulation as a shared pathogenic mechanism in genetically distinct ASD cases55,56. The inhibition of aberrant translation directly via compounds targeting translation factors (for example, 4EGI-157) or by modulating the mTOR pathway58 has been shown to prevent autism-relevant phenotypes in mice and has been proposed as a therapeutic strategy to correct dysregulated protein synthesis in ASD58.
AS is co- or post-transcriptionally regulated by RNA-binding proteins (RBPs) and tightly controlled during developmental stages in a tissue-specific manner59. Given the limited number of protein-coding genes in the human genome, AS is recognized as an essential source of transcriptomic and proteomic diversity driving the species-specific features of the human brain60–62. Dysregulation of AS in post-mortem brain tissue from ASD patients with distinct etiologies has been increasingly apparent as a convergent mechanism in ASD63–65. The transcripts that are misspliced in ASD are enriched for neuronal RBP targets, including those of RBFOX163,65, SRRM465, and PTBP165, suggesting that defective RBP function is a common feature of ASD. Genetic evidence showing ASD-linked chromosomal translocations and copy number variations in RBFOX1 also supports a prominent role for loss or dysregulation (or both) of RBFOX1 activity in ASD pathogenesis13,66–68. Loss of RBFOX1 in mice causes deficits in synaptic transmission69 and corticogenesis70. Neuronal-specific, activity-dependent, 3- to 27-nucleotide microexons are frequently misspliced in ASD64,71. This group of genes that are subject to microexon splicing is enriched for synaptic functions and ASD genes64,71. These microexons are regulated primarily by the neuronal RBP, SRRM4, which is downregulated in ASD brains64. Haploinsufficiency of SRRM4 in mice resulted in microexon misregulation and ASD-like features, including altered social behaviors71. These data highlight the function of RBPs, including RBFOX1 and SRRM4, as essential for cortical development and function and at risk in ASD. Taken together, global dysregulation of RNA processing and protein translation is likely to be a common feature of genetically diverse ASD cases, and the regulation of these processes might be a viable target for therapeutic approaches.
Patient-specific disease models
The high degree of genetic heterogeneity in ASD requires personalized approaches to understand the underlying individual pathogenic mechanisms and develop efficient treatments. In addition, there is a need for improved model systems with appropriate genetic backgrounds to test identified convergent biological mechanisms such as the ones discussed above. Advances in stem cell biology in the last decade have yielded protocols for the generation of human neurons from accessible somatic tissue (for example, skin), overcoming the unavailability of human neurons from specific developmental stages or disease states. Briefly, human induced pluripotent stem cells (hiPSCs) are generated by the ectopic expression of specific transcription factors in somatic cells that then can be differentiated into neurons or glia harboring the genetic features of the human individual from whom the cells are derived, either the patients or matched unaffected controls72. In addition, isogenic neurons generated by introducing mutations in control iPSCs via gene editing technologies—that is, CRISPR-Cas973,74 and TALENs75—can be used to study the functional impact of disease-related mutations on a non-disease genetic background.
Research adopting iPSC-based models has begun to impact the understanding of the biological underpinnings of several ASD-related genetic variants76,77. In several instances, syndromic forms of ASD, including Fragile X78,79, Rett80, Timothy81,82, and Phelan–McDermid83 syndromes, have been modeled by using iPSCs. These studies have defined disease-related defects in patient-derived neurons, including reduced synaptic density, impaired excitatory transmission, and aberrant signaling. Additionally, a recent study of iPSCs from an ASD patient with a de novo mutation in TRPC6 confirmed the potential for patient-specific disease modeling of rare ASD variants84.
Breakthroughs in iPSC culture systems have facilitated the generation of more complex differentiation programs that yield organ-like structures. These 3D brain organoids have been established with the goal of improved recapitulation of brain development and connectivity in vitro, providing an unprecedented opportunity to study human brain features in a dish85–87. A major goal of using patient-derived 3D organoids is to perform high-throughput drug screens to correct ASD-relevant cellular defects and reliably predict drug responses specific to each individual. In the future, standardization of 3D human brain organoid generation is needed for reliable and reproducible disease modeling. Defining the functional properties and molecular signatures of brain organoids derived from unaffected iPSCs at several time points will provide insights into how this model system follows in vivo human brain development and baseline information for disease modeling. It will be important to address how the differentiation process of 3D brain organoids corresponds to stages of human brain development. This will be essential to identify and translate the critical time window for successful therapeutic intervention. Recent advances in single-cell RNA sequencing facilitate the identification of cell types and differentiation states of diverse human neuronal populations in fetal brain in vivo88 and have also proven to be very useful for characterizing brain organoids89. Integration of cell-specific gene expression profiles with regional and developmental timing mechanisms has been elegantly carried out from human fetal tissue88, and these data can be superimposed on the data derived from patient organoids to identify aberrant profiles. Inherent limitations of 3D brain organoids such as lack of behavioral output and circuit-based studies should be addressed with complementary studies using animal models19.
In terms of cell-specific profiling, most research has gone into characterizing the neuronal defects in ASD; however, the involvement of glia has recently been implicated in many neuropsychiatric diseases90. For example, a recent iPSC model provided evidence that defects in astrocytes can contribute to non-syndromic ASD91 with unknown genetic cause. Therefore, future strategies to develop therapies for ASD should not only focus on neurons but also include all cell types in the brain. In addition, these data support the promise of using iPSC models from individuals with genetically complex etiologies to narrow the therapeutic search window to common pathogenic mechanisms. Improvements to brain organoid models that include many cell types such as glia and endothelial cells from non-syndromic ASD patients should further facilitate the identification of patient-specific cellular deficits.
Conclusions
Technological and conceptual advances in genomics, stem cell biology, and gene editing together with large cohorts of patients are providing opportunities to identify genetic causes of ASD and develop functionally relevant disease models. Integrative studies that include post-mortem tissue, genomics, and single-cell transcriptomics will continue to provide insights into human brain development and how this process is disrupted in ASD. By improved modeling of the disease using patient tissues and incorporating data from genomic and gene expression studies into these models, the field should move closer to developing personalized therapeutic approaches as well as identifying common druggable molecular pathways. Thus, persistent pursuit of all of the strategies discussed above will be needed to define optimal personalized treatments that potentially could involve several drugs in combination for additive or synergistic effects.
Abbreviations
3D, three-dimensional; AS, alternative splicing; ASD, autism spectrum disorder; CNV, copy number variant; hiPSC, human induced pluripotent stem cell; mTOR, mammalian target of rapamycin; RBP, RNA-binding protein; SNV, single-nucleotide variant; WES, whole exome sequencing.
Competing interests
No competing interests were disclosed.
Grant information
This work is supported by grants from the National Institutes of Health (R01DC014702 and R01MH102603 to GK and T32DA007290-24 to FA), the Simons Foundation Autism Research Initiative (project 401220 to GK), and a James S. McDonnell Foundation 21st Century Science Initiative in Understanding Human Cognition – Scholar Award to GK.
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Acknowledgments
The authors wish to thank Maria Chahrour for her helpful comments and suggestions. GK is a Jon Heighten Scholar in Autism Research at UT Southwestern.
F1000 recommended
References
1.
American Psychiatric Association:
Diagnostic and Statistical Manual of Mental Disorders: DSM-5. 5th edn. American Psychiatric Association, Arlington, Virginia, USA 2013. Publisher Full Text
2.
Christensen DL, Baio J, Van Naarden Braun K, et al.:
Prevalence and Characteristics of Autism Spectrum Disorder Among Children Aged 8 Years--Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2012.
MMWR Surveill Summ.
2016; 65(3): 1–23. PubMed Abstract
| Publisher Full Text
3.
Kim YS, Leventhal BL:
Genetic epidemiology and insights into interactive genetic and environmental effects in autism spectrum disorders.
Biol Psychiatry.
2015; 77(1): 66–74. PubMed Abstract
| Publisher Full Text
| Free Full Text
4.
Rosenberg RE, Law JK, Yenokyan G, et al.:
Characteristics and concordance of autism spectrum disorders among 277 twin pairs.
Arch Pediatr Adolesc Med.
2009; 163(10): 907–14. PubMed Abstract
| Publisher Full Text
5.
Bailey A, Le Couteur A, Gottesman I, et al.:
Autism as a strongly genetic disorder: evidence from a British twin study.
Psychol. Med.
1995; 25(1): 63–77. PubMed Abstract
| Publisher Full Text
9.
Colvert E, Tick B, McEwen F, et al.:
Heritability of Autism Spectrum Disorder in a UK Population-Based Twin Sample.
JAMA Psychiatry.
2015; 72(5): 415–23. PubMed Abstract
| Publisher Full Text
| Free Full Text
12.
C Yuen RK, Merico D, Bookman M, et al.:
Whole genome sequencing resource identifies 18 new candidate genes for autism spectrum disorder.
Nat Neurosci.
2017; 20(4): 602–11. PubMed Abstract
| Publisher Full Text
| Free Full Text
14.
Sanders SJ, Ercan-Sencicek AG, Hus V, et al.:
Multiple recurrent de novo CNVs, including duplications of the 7q11.23 Williams syndrome region, are strongly associated with autism.
Neuron.
2011; 70(5): 863–85. PubMed Abstract
| Publisher Full Text
| Free Full Text
| F1000 Recommendation
15.
Gilman SR, Iossifov I, Levy D, et al.:
Rare de novo variants associated with autism implicate a large functional network of genes involved in formation and function of synapses.
Neuron.
2011; 70(5): 898–907. PubMed Abstract
| Publisher Full Text
| Free Full Text
19.
Chahrour M, O'Roak BJ, Santini E, et al.:
Current Perspectives in Autism Spectrum Disorder: From Genes to Therapy.
J Neurosci.
2016; 36(45): 11402–10. PubMed Abstract
| Publisher Full Text
| Free Full Text
21.
O'Roak BJ, Stessman HA, Boyle EA, et al.:
Recurrent de novo mutations implicate novel genes underlying simplex autism risk.
Nat Commun.
2014; 5: 5595. PubMed Abstract
| Publisher Full Text
| Free Full Text
22.
Verkerk AJ, Pieretti M, Sutcliffe JS, et al.:
Identification of a gene (FMR-1) containing a CGG repeat coincident with a breakpoint cluster region exhibiting length variation in fragile X syndrome.
Cell.
1991; 65(5): 905–14. PubMed Abstract
| Publisher Full Text
23.
Amir RE, Van den Veyver IB, Wan M, et al.:
Rett syndrome is caused by mutations in X-linked MECP2, encoding methyl-CpG-binding protein 2.
Nat Genet.
1999; 23(2): 185–8. PubMed Abstract
| Publisher Full Text
24.
Van Esch H, Bauters M, Ignatius J, et al.:
Duplication of the MECP2 region is a frequent cause of severe mental retardation and progressive neurological symptoms in males.
Am J Hum Genet.
2005; 77(3): 442–53. PubMed Abstract
| Publisher Full Text
| Free Full Text
| F1000 Recommendation
25.
Fryer AE, Chalmers A, Connor JM, et al.:
Evidence that the gene for tuberous sclerosis is on chromosome 9.
Lancet.
1987; 1(8534): 659–61. PubMed Abstract
| Publisher Full Text
26.
Butler MG, Dasouki MJ, Zhou XP, et al.:
Subset of individuals with autism spectrum disorders and extreme macrocephaly associated with germline PTEN tumour suppressor gene mutations.
J Med Genet.
2005; 42(4): 318–21. PubMed Abstract
| Publisher Full Text
| Free Full Text
27.
Splawski I, Timothy KW, Sharpe LM, et al.:
CaV1.2 calcium channel dysfunction causes a multisystem disorder including arrhythmia and autism.
Cell.
2004; 119(1): 19–31. PubMed Abstract
| Publisher Full Text
| F1000 Recommendation
32.
Manzini MC, Xiong L, Shaheen R, et al.:
CC2D1A regulates human intellectual and social function as well as NF-κB signaling homeostasis.
Cell Rep.
2014; 8(3): 647–55. PubMed Abstract
| Publisher Full Text
| Free Full Text
34.
Chahrour MH, Yu TW, Lim ET, et al.:
Whole-exome sequencing and homozygosity analysis implicate depolarization-regulated neuronal genes in autism.
PLoS Genet.
2012; 8(4): e1002635. PubMed Abstract
| Publisher Full Text
| Free Full Text
36.
Iossifov I, O'Roak BJ, Sanders SJ, et al.:
The contribution of de novo coding mutations to autism spectrum disorder.
Nature.
2014; 515(7526): 216–21. PubMed Abstract
| Publisher Full Text
| Free Full Text
40.
Hamdan FF, Daoud H, Piton A, et al.:
De novoSYNGAP1 mutations in nonsyndromic intellectual disability and autism.
Biol Psychiatry.
2011; 69(9): 898–901. PubMed Abstract
| Publisher Full Text
41.
Parker MJ, Fryer AE, Shears DJ, et al.:
De novo, heterozygous, loss-of-function mutations in SYNGAP1 cause a syndromic form of intellectual disability.
Am J Med Genet A.
2015; 167A(10): 2231–7. PubMed Abstract
| Publisher Full Text
| Free Full Text
42.
van Bon BW, Coe BP, Bernier R, et al.:
Disruptive de novo mutations of DYRK1A lead to a syndromic form of autism and ID.
Mol Psychiatry.
2016; 21(1): 126–32. PubMed Abstract
| Publisher Full Text
| Free Full Text
48.
McConnell MJ, Moran JV, Abyzov A, et al.:
Intersection of diverse neuronal genomes and neuropsychiatric disease: The Brain Somatic Mosaicism Network.
Science.
2017; 356(6336): pii: eaal1641. PubMed Abstract
| Publisher Full Text
| Free Full Text
49.
de la Torre-Ubieta L, Won H, Stein JL, et al.:
Advancing the understanding of autism disease mechanisms through genetics.
Nat Med.
2016; 22(4): 345–61. PubMed Abstract
| Publisher Full Text
| Free Full Text
50.
Buffington SA, Huang W, Costa-Mattioli M:
Translational control in synaptic plasticity and cognitive dysfunction.
Annu Rev Neurosci.
2014; 37: 17–38. PubMed Abstract
| Publisher Full Text
| Free Full Text
53.
Jeste SS, Sahin M, Bolton P, et al.:
Characterization of autism in young children with tuberous sclerosis complex.
J Child Neurol.
2008; 23(5): 520–5. PubMed Abstract
| Publisher Full Text
54.
Krumm N, O'Roak BJ, Shendure J, et al.:
A de novo convergence of autism genetics and molecular neuroscience.
Trends Neurosci.
2014; 37(2): 95–105. PubMed Abstract
| Publisher Full Text
| Free Full Text
55.
Suzuki AM, Griesi-Oliveira K, de Oliveira Freitas Machado C, et al.:
Altered mTORC1 signaling in multipotent stem cells from nearly 25% of patients with nonsyndromic autism spectrum disorders.
Mol Psychiatry.
2015; 20(5): 551–2. PubMed Abstract
| Publisher Full Text
| F1000 Recommendation
56.
Poopal AC, Schroeder LM, Horn PS, et al.:
Increased expression of the PI3K catalytic subunit p110δ underlies elevated S6 phosphorylation and protein synthesis in an individual with autism from a multiplex family.
Mol Autism.
2016; 7: 3. PubMed Abstract
| Publisher Full Text
| Free Full Text
| F1000 Recommendation
57.
Santini E, Huynh TN, MacAskill AF, et al.:
Exaggerated translation causes synaptic and behavioural aberrations associated with autism.
Nature.
2013; 493(7432): 411–5. PubMed Abstract
| Publisher Full Text
| Free Full Text
60.
Pan Q, Shai O, Lee LJ, et al.:
Deep surveying of alternative splicing complexity in the human transcriptome by high-throughput sequencing.
Nat Genet.
2008; 40(12): 1413–5. PubMed Abstract
| Publisher Full Text
65.
Parikshak NN, Swarup V, Belgard TG, et al.:
Genome-wide changes in lncRNA, splicing, and regional gene expression patterns in autism.
Nature.
2016; 540(7633): 423–7. PubMed Abstract
| Publisher Full Text
66.
Martin CL, Duvall JA, Ilkin Y, et al.:
Cytogenetic and molecular characterization of A2BP1/FOX1 as a candidate gene for autism.
Am J Med Genet B Neuropsychiatr Genet.
2007; 144B(7): 869–76. PubMed Abstract
| Publisher Full Text
67.
Mikhail FM, Lose EJ, Robin NH, et al.:
Clinically relevant single gene or intragenic deletions encompassing critical neurodevelopmental genes in patients with developmental delay, mental retardation, and/or autism spectrum disorders.
Am J Med Genet A.
2011; 155A(10): 2386–96. PubMed Abstract
| Publisher Full Text
68.
Davis LK, Maltman N, Mosconi MW, et al.:
Rare inherited A2BP1 deletion in a proband with autism and developmental hemiparesis.
Am J Med Genet A.
2012; 158A(7): 1654–61. PubMed Abstract
| Publisher Full Text
| Free Full Text
69.
Gehman LT, Stoilov P, Maguire J, et al.:
The splicing regulator Rbfox1 (A2BP1) controls neuronal excitation in the mammalian brain.
Nat Genet.
2011; 43(7): 706–11. PubMed Abstract
| Publisher Full Text
| Free Full Text
70.
Hamada N, Ito H, Iwamoto I, et al.:
Role of the cytoplasmic isoform of RBFOX1/A2BP1 in establishing the architecture of the developing cerebral cortex.
Mol Autism.
2015; 6: 56. PubMed Abstract
| Publisher Full Text
| Free Full Text
71.
Quesnel-Vallières M, Dargaei Z, Irimia M, et al.:
Misregulation of an Activity-Dependent Splicing Network as a Common Mechanism Underlying Autism Spectrum Disorders.
Mol Cell.
2016; 64(6): 1023–34. PubMed Abstract
| Publisher Full Text
| F1000 Recommendation
72.
Paşca SP, Panagiotakos G, Dolmetsch RE:
Generating human neurons in vitro and using them to understand neuropsychiatric disease.
Annu Rev Neurosci.
2014; 37: 479–501. PubMed Abstract
| Publisher Full Text
75.
Miller JC, Tan S, Qiao G, et al.:
A TALE nuclease architecture for efficient genome editing.
Nat Biotechnol.
2011; 29(2): 143–8. PubMed Abstract
| Publisher Full Text
76.
Nestor MW, Phillips AW, Artimovich E, et al.:
Human Inducible Pluripotent Stem Cells and Autism Spectrum Disorder: Emerging Technologies.
Autism Res.
2016; 9(5): 513–35. PubMed Abstract
| Publisher Full Text
| F1000 Recommendation
79.
Doers ME, Musser MT, Nichol R, et al.:
iPSC-derived forebrain neurons from FXS individuals show defects in initial neurite outgrowth.
Stem Cells Dev.
2014; 23(15): 1777–87. PubMed Abstract
| Publisher Full Text
| Free Full Text
81.
Tian Y, Voineagu I, Paşca SP, et al.:
Alteration in basal and depolarization induced transcriptional network in iPSC derived neurons from Timothy syndrome.
Genome Med.
2014; 6(10): 75. PubMed Abstract
| Publisher Full Text
| Free Full Text
82.
Krey JF, Paşca SP, Shcheglovitov A, et al.:
Timothy syndrome is associated with activity-dependent dendritic retraction in rodent and human neurons.
Nat Neurosci.
2013; 16(2): 201–9. PubMed Abstract
| Publisher Full Text
| Free Full Text
86.
Giandomenico SL, Lancaster MA:
Probing human brain evolution and development in organoids.
Curr Opin Cell Biol.
2017; 44: 36–43. PubMed Abstract
| Publisher Full Text
87.
Camp JG, Treutlein B:
Human organomics: a fresh approach to understanding human development using single-cell transcriptomics.
Development.
2017; 144(9): 1584–7. PubMed Abstract
| Publisher Full Text
88.
Nowakowski TJ, Bhaduri A, Pollen AA, et al.:
Spatiotemporal gene expression trajectories reveal developmental hierarchies of the human cortex.
Science.
2017; 358: 1318–23. PubMed Abstract
| Publisher Full Text
| F1000 Recommendation
90.
Salter MW, Stevens B:
Microglia emerge as central players in brain disease.
Nat Med.
2017; 23(9): 1018–27. PubMed Abstract
| Publisher Full Text
91.
Russo FB, Freitas BC, Pignatari GC, et al.:
Modeling the Interplay Between Neurons and Astrocytes in Autism Using Human Induced Pluripotent Stem Cells.
Biol Psychiatry.
2018; 83(7): 569–78. PubMed Abstract
| Publisher Full Text
| F1000 Recommendation
Comments on this articleComments (1)
Version 1
VERSION 1PUBLISHED 22 May 2018
Reader Comment
29 May 2018
James Lyons-Weiler, Institute for Pure and Applied Knowledge, USA
29 May 2018
Reader Comment
"family and twin studies show that genetics contribute to the majority of the risk associated with ASD"
This is one interpretation, but it is incorrect on two counts. The majority of
...
Continue reading"family and twin studies show that genetics contribute to the majority of the risk associated with ASD"
This is one interpretation, but it is incorrect on two counts. The majority of heritable studies actually show similar levels of contributed risk from genes and the environment, including those that did not measure any environmental factors. Since no studies have examined the role of environmental factors and genetic factors in the same populations, the significance of risk from genetic x environment interaction has never been measured. Further attributing risk to genetics alone in heritability studies likely conflates heritable variation in brain attributes that are also heritable in the neurotypical population, and the overall genetic contribution is likely exaggerated. This would include neurological differences whose effects are altered in the presence of ubiquitous environmental toxins. By analogy, if everyone smoked, lung cancer would appear to be genetic.
Some of the heritability appears to be due to heritability of susceptibility to environmental toxins. The list of environmental toxins implicated by studies to date are numerous and varied, pointing to a cellular detoxification deficiency syndrome with altered metal detoxification, and, importantly, increased ER stress response and altered Unfolded Protein Response outcomes[1]. Autistics' have altered blood/brain and intestinal barrier functions[2], meaning they belong to a subset of people who cannot handle toxins from various sources as well as others.
We recently found that the FDA and the HHS both erred in their determination that the amount of aluminum in vaccines is 'safe' in the first six months of life [3]. Masson et al. (2018) similarly found flaws and unwarranted assumptions in two key studies[4]. "Genetic" interpretations of findings of signs of neurological difference in ASD prior to birth ignore the CDC's policy shift to promote vaccination during pregnancy[5]. This practice, which now involves thimerosal-containing flu vaccines, TdaP (primarily for pertussis), and others as needed [5] is conducted contra FDA approval and, in the case of pertussis, against product labeling. If mothers of children at risk of ASD also have cellular detoxification deficiency, the "genetic" aspect of ASD likely involves (partly) environmental susceptibility genes. Uptake of toxins from diet via a compromised gut lining, likely due to activated enteric microglia, will compound the effects of other sources of toxins.
The environmental susceptibility variation contributing ASD risk can include variation in protein-coding genes that alters their intrinsic disorder, making them more difficult to fold in the endoplasmic reticulum (ER), leading to genetically induced ER stress. Importantly, the protein or protein(s) involved can have any cellular function. Both thimerosal and aluminum cause ER stress, mitochondrial dysfunction, and impaired Golgi functions, all essential for proper cellular detoxification[1]. This means ASD individuals will tend to acquire a variety of types of toxins - and this has been observed, with levels predictive of severity of behavior [6].
The combined effects of genetic ER stress and environmentally induced ER stress is called ER Hyperstress[1], favoring ER overload (over reduction in transcription or translation), forcing the UPR to conclude via apoptosis independent of p53, release of cytokines, and re-distribution of toxins bound to cellular debris, which are picked up by macrophages which locate these metals to the periphery of the brain. Aluminum has been found in the brain of people with ASD[7].
Multiple chemical sensitivity is commonly reported in people with autism and is on the increase throughout the general population[8]. With ASD now estimated at 1 in 59, and 1 in 37 in boys [9], there is simply no plausible mechanism for a "mostly genetic" condition to appear within 1-1.5 generations,
For more citations on the cellular processes implicating environmental toxins via the ER Hyperstress/Cellular Detoxification Deficiency Model of ASD, see [10].
We can no longer afford to study G alone, E alone, and ignore G x E in ASD and other neurodevelopmental disorders. Future genetic studies should examine risk of environmental susceptibility in ASD, and include all sources of toxins.
"family and twin studies show that genetics contribute to the majority of the risk associated with ASD"
This is one interpretation, but it is incorrect on two counts. The majority of heritable studies actually show similar levels of contributed risk from genes and the environment, including those that did not measure any environmental factors. Since no studies have examined the role of environmental factors and genetic factors in the same populations, the significance of risk from genetic x environment interaction has never been measured. Further attributing risk to genetics alone in heritability studies likely conflates heritable variation in brain attributes that are also heritable in the neurotypical population, and the overall genetic contribution is likely exaggerated. This would include neurological differences whose effects are altered in the presence of ubiquitous environmental toxins. By analogy, if everyone smoked, lung cancer would appear to be genetic.
Some of the heritability appears to be due to heritability of susceptibility to environmental toxins. The list of environmental toxins implicated by studies to date are numerous and varied, pointing to a cellular detoxification deficiency syndrome with altered metal detoxification, and, importantly, increased ER stress response and altered Unfolded Protein Response outcomes[1]. Autistics' have altered blood/brain and intestinal barrier functions[2], meaning they belong to a subset of people who cannot handle toxins from various sources as well as others.
We recently found that the FDA and the HHS both erred in their determination that the amount of aluminum in vaccines is 'safe' in the first six months of life [3]. Masson et al. (2018) similarly found flaws and unwarranted assumptions in two key studies[4]. "Genetic" interpretations of findings of signs of neurological difference in ASD prior to birth ignore the CDC's policy shift to promote vaccination during pregnancy[5]. This practice, which now involves thimerosal-containing flu vaccines, TdaP (primarily for pertussis), and others as needed [5] is conducted contra FDA approval and, in the case of pertussis, against product labeling. If mothers of children at risk of ASD also have cellular detoxification deficiency, the "genetic" aspect of ASD likely involves (partly) environmental susceptibility genes. Uptake of toxins from diet via a compromised gut lining, likely due to activated enteric microglia, will compound the effects of other sources of toxins.
The environmental susceptibility variation contributing ASD risk can include variation in protein-coding genes that alters their intrinsic disorder, making them more difficult to fold in the endoplasmic reticulum (ER), leading to genetically induced ER stress. Importantly, the protein or protein(s) involved can have any cellular function. Both thimerosal and aluminum cause ER stress, mitochondrial dysfunction, and impaired Golgi functions, all essential for proper cellular detoxification[1]. This means ASD individuals will tend to acquire a variety of types of toxins - and this has been observed, with levels predictive of severity of behavior [6].
The combined effects of genetic ER stress and environmentally induced ER stress is called ER Hyperstress[1], favoring ER overload (over reduction in transcription or translation), forcing the UPR to conclude via apoptosis independent of p53, release of cytokines, and re-distribution of toxins bound to cellular debris, which are picked up by macrophages which locate these metals to the periphery of the brain. Aluminum has been found in the brain of people with ASD[7].
Multiple chemical sensitivity is commonly reported in people with autism and is on the increase throughout the general population[8]. With ASD now estimated at 1 in 59, and 1 in 37 in boys [9], there is simply no plausible mechanism for a "mostly genetic" condition to appear within 1-1.5 generations,
For more citations on the cellular processes implicating environmental toxins via the ER Hyperstress/Cellular Detoxification Deficiency Model of ASD, see [10].
We can no longer afford to study G alone, E alone, and ignore G x E in ASD and other neurodevelopmental disorders. Future genetic studies should examine risk of environmental susceptibility in ASD, and include all sources of toxins.
Competing Interests:I have served as expert witness on various cases under consideration by the National Vaccine Injury Compensation Program, but none of those cases involve ASD or other neurodevelopmental disorders.Close
This work is supported by grants from the National Institutes of Health (R01DC014702 and R01MH102603 to GK and T32DA007290-24 to FA), the Simons Foundation Autism Research Initiative (project 401220 to GK), and a James S. McDonnell Foundation 21st Century Science Initiative in Understanding Human Cognition – Scholar Award to GK.
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Ayhan F and Konopka G. Genomics of autism spectrum disorder: approach to therapy [version 1; peer review: 3 approved] F1000Research 2018, 7(F1000 Faculty Rev):627 (https://doi.org/10.12688/f1000research.13865.1)
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Reviewer Report22 May 2018
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Competing Interests: No competing interests were disclosed.
Faculty Reviews are commissioned and written by members of the prestigious Faculty Opinions Faculty, and are edited as a service to our readers. In order to make these reviews as comprehensive and accessible as possible, we seek the reviewers’ input before publication. The reviewers’ names and any additional comments they may have are published alongside the review, as is usual on F1000Research.
I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.
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Reviewer Report22 May 2018
Alysson R. Muotri, Department of Pediatrics/Rady Children׳s Hospital San Diego, Department of Cellular & Molecular Medicine, Stem Cell Program, School of Medicine, University of California San Diego, La Jolla, CA, USA
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Competing Interests: No competing interests were disclosed.
Faculty Reviews are commissioned and written by members of the prestigious Faculty Opinions Faculty, and are edited as a service to our readers. In order to make these reviews as comprehensive and accessible as possible, we seek the reviewers’ input before publication. The reviewers’ names and any additional comments they may have are published alongside the review, as is usual on F1000Research.
I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.
James Lyons-Weiler, Institute for Pure and Applied Knowledge, USA
29 May 2018
Reader Comment
"family and twin studies show that genetics contribute to the majority of the risk associated with ASD"
This is one interpretation, but it is incorrect on two counts. The majority of
...
Continue reading"family and twin studies show that genetics contribute to the majority of the risk associated with ASD"
This is one interpretation, but it is incorrect on two counts. The majority of heritable studies actually show similar levels of contributed risk from genes and the environment, including those that did not measure any environmental factors. Since no studies have examined the role of environmental factors and genetic factors in the same populations, the significance of risk from genetic x environment interaction has never been measured. Further attributing risk to genetics alone in heritability studies likely conflates heritable variation in brain attributes that are also heritable in the neurotypical population, and the overall genetic contribution is likely exaggerated. This would include neurological differences whose effects are altered in the presence of ubiquitous environmental toxins. By analogy, if everyone smoked, lung cancer would appear to be genetic.
Some of the heritability appears to be due to heritability of susceptibility to environmental toxins. The list of environmental toxins implicated by studies to date are numerous and varied, pointing to a cellular detoxification deficiency syndrome with altered metal detoxification, and, importantly, increased ER stress response and altered Unfolded Protein Response outcomes[1]. Autistics' have altered blood/brain and intestinal barrier functions[2], meaning they belong to a subset of people who cannot handle toxins from various sources as well as others.
We recently found that the FDA and the HHS both erred in their determination that the amount of aluminum in vaccines is 'safe' in the first six months of life [3]. Masson et al. (2018) similarly found flaws and unwarranted assumptions in two key studies[4]. "Genetic" interpretations of findings of signs of neurological difference in ASD prior to birth ignore the CDC's policy shift to promote vaccination during pregnancy[5]. This practice, which now involves thimerosal-containing flu vaccines, TdaP (primarily for pertussis), and others as needed [5] is conducted contra FDA approval and, in the case of pertussis, against product labeling. If mothers of children at risk of ASD also have cellular detoxification deficiency, the "genetic" aspect of ASD likely involves (partly) environmental susceptibility genes. Uptake of toxins from diet via a compromised gut lining, likely due to activated enteric microglia, will compound the effects of other sources of toxins.
The environmental susceptibility variation contributing ASD risk can include variation in protein-coding genes that alters their intrinsic disorder, making them more difficult to fold in the endoplasmic reticulum (ER), leading to genetically induced ER stress. Importantly, the protein or protein(s) involved can have any cellular function. Both thimerosal and aluminum cause ER stress, mitochondrial dysfunction, and impaired Golgi functions, all essential for proper cellular detoxification[1]. This means ASD individuals will tend to acquire a variety of types of toxins - and this has been observed, with levels predictive of severity of behavior [6].
The combined effects of genetic ER stress and environmentally induced ER stress is called ER Hyperstress[1], favoring ER overload (over reduction in transcription or translation), forcing the UPR to conclude via apoptosis independent of p53, release of cytokines, and re-distribution of toxins bound to cellular debris, which are picked up by macrophages which locate these metals to the periphery of the brain. Aluminum has been found in the brain of people with ASD[7].
Multiple chemical sensitivity is commonly reported in people with autism and is on the increase throughout the general population[8]. With ASD now estimated at 1 in 59, and 1 in 37 in boys [9], there is simply no plausible mechanism for a "mostly genetic" condition to appear within 1-1.5 generations,
For more citations on the cellular processes implicating environmental toxins via the ER Hyperstress/Cellular Detoxification Deficiency Model of ASD, see [10].
We can no longer afford to study G alone, E alone, and ignore G x E in ASD and other neurodevelopmental disorders. Future genetic studies should examine risk of environmental susceptibility in ASD, and include all sources of toxins.
"family and twin studies show that genetics contribute to the majority of the risk associated with ASD"
This is one interpretation, but it is incorrect on two counts. The majority of heritable studies actually show similar levels of contributed risk from genes and the environment, including those that did not measure any environmental factors. Since no studies have examined the role of environmental factors and genetic factors in the same populations, the significance of risk from genetic x environment interaction has never been measured. Further attributing risk to genetics alone in heritability studies likely conflates heritable variation in brain attributes that are also heritable in the neurotypical population, and the overall genetic contribution is likely exaggerated. This would include neurological differences whose effects are altered in the presence of ubiquitous environmental toxins. By analogy, if everyone smoked, lung cancer would appear to be genetic.
Some of the heritability appears to be due to heritability of susceptibility to environmental toxins. The list of environmental toxins implicated by studies to date are numerous and varied, pointing to a cellular detoxification deficiency syndrome with altered metal detoxification, and, importantly, increased ER stress response and altered Unfolded Protein Response outcomes[1]. Autistics' have altered blood/brain and intestinal barrier functions[2], meaning they belong to a subset of people who cannot handle toxins from various sources as well as others.
We recently found that the FDA and the HHS both erred in their determination that the amount of aluminum in vaccines is 'safe' in the first six months of life [3]. Masson et al. (2018) similarly found flaws and unwarranted assumptions in two key studies[4]. "Genetic" interpretations of findings of signs of neurological difference in ASD prior to birth ignore the CDC's policy shift to promote vaccination during pregnancy[5]. This practice, which now involves thimerosal-containing flu vaccines, TdaP (primarily for pertussis), and others as needed [5] is conducted contra FDA approval and, in the case of pertussis, against product labeling. If mothers of children at risk of ASD also have cellular detoxification deficiency, the "genetic" aspect of ASD likely involves (partly) environmental susceptibility genes. Uptake of toxins from diet via a compromised gut lining, likely due to activated enteric microglia, will compound the effects of other sources of toxins.
The environmental susceptibility variation contributing ASD risk can include variation in protein-coding genes that alters their intrinsic disorder, making them more difficult to fold in the endoplasmic reticulum (ER), leading to genetically induced ER stress. Importantly, the protein or protein(s) involved can have any cellular function. Both thimerosal and aluminum cause ER stress, mitochondrial dysfunction, and impaired Golgi functions, all essential for proper cellular detoxification[1]. This means ASD individuals will tend to acquire a variety of types of toxins - and this has been observed, with levels predictive of severity of behavior [6].
The combined effects of genetic ER stress and environmentally induced ER stress is called ER Hyperstress[1], favoring ER overload (over reduction in transcription or translation), forcing the UPR to conclude via apoptosis independent of p53, release of cytokines, and re-distribution of toxins bound to cellular debris, which are picked up by macrophages which locate these metals to the periphery of the brain. Aluminum has been found in the brain of people with ASD[7].
Multiple chemical sensitivity is commonly reported in people with autism and is on the increase throughout the general population[8]. With ASD now estimated at 1 in 59, and 1 in 37 in boys [9], there is simply no plausible mechanism for a "mostly genetic" condition to appear within 1-1.5 generations,
For more citations on the cellular processes implicating environmental toxins via the ER Hyperstress/Cellular Detoxification Deficiency Model of ASD, see [10].
We can no longer afford to study G alone, E alone, and ignore G x E in ASD and other neurodevelopmental disorders. Future genetic studies should examine risk of environmental susceptibility in ASD, and include all sources of toxins.
Competing Interests:I have served as expert witness on various cases under consideration by the National Vaccine Injury Compensation Program, but none of those cases involve ASD or other neurodevelopmental disorders.Close
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This is one interpretation, but it is incorrect on two counts. The majority of ... Continue reading "family and twin studies show that genetics contribute to the majority of the risk associated with ASD"
This is one interpretation, but it is incorrect on two counts. The majority of heritable studies actually show similar levels of contributed risk from genes and the environment, including those that did not measure any environmental factors. Since no studies have examined the role of environmental factors and genetic factors in the same populations, the significance of risk from genetic x environment interaction has never been measured. Further attributing risk to genetics alone in heritability studies likely conflates heritable variation in brain attributes that are also heritable in the neurotypical population, and the overall genetic contribution is likely exaggerated. This would include neurological differences whose effects are altered in the presence of ubiquitous environmental toxins. By analogy, if everyone smoked, lung cancer would appear to be genetic.
Some of the heritability appears to be due to heritability of susceptibility to environmental toxins. The list of environmental toxins implicated by studies to date are numerous and varied, pointing to a cellular detoxification deficiency syndrome with altered metal detoxification, and, importantly, increased ER stress response and altered Unfolded Protein Response outcomes[1]. Autistics' have altered blood/brain and intestinal barrier functions[2], meaning they belong to a subset of people who cannot handle toxins from various sources as well as others.
We recently found that the FDA and the HHS both erred in their determination that the amount of aluminum in vaccines is 'safe' in the first six months of life [3]. Masson et al. (2018) similarly found flaws and unwarranted assumptions in two key studies[4]. "Genetic" interpretations of findings of signs of neurological difference in ASD prior to birth ignore the CDC's policy shift to promote vaccination during pregnancy[5]. This practice, which now involves thimerosal-containing flu vaccines, TdaP (primarily for pertussis), and others as needed [5] is conducted contra FDA approval and, in the case of pertussis, against product labeling. If mothers of children at risk of ASD also have cellular detoxification deficiency, the "genetic" aspect of ASD likely involves (partly) environmental susceptibility genes. Uptake of toxins from diet via a compromised gut lining, likely due to activated enteric microglia, will compound the effects of other sources of toxins.
The environmental susceptibility variation contributing ASD risk can include variation in protein-coding genes that alters their intrinsic disorder, making them more difficult to fold in the endoplasmic reticulum (ER), leading to genetically induced ER stress. Importantly, the protein or protein(s) involved can have any cellular function. Both thimerosal and aluminum cause ER stress, mitochondrial dysfunction, and impaired Golgi functions, all essential for proper cellular detoxification[1]. This means ASD individuals will tend to acquire a variety of types of toxins - and this has been observed, with levels predictive of severity of behavior [6].
The combined effects of genetic ER stress and environmentally induced ER stress is called ER Hyperstress[1], favoring ER overload (over reduction in transcription or translation), forcing the UPR to conclude via apoptosis independent of p53, release of cytokines, and re-distribution of toxins bound to cellular debris, which are picked up by macrophages which locate these metals to the periphery of the brain. Aluminum has been found in the brain of people with ASD[7].
Multiple chemical sensitivity is commonly reported in people with autism and is on the increase throughout the general population[8]. With ASD now estimated at 1 in 59, and 1 in 37 in boys [9], there is simply no plausible mechanism for a "mostly genetic" condition to appear within 1-1.5 generations,
For more citations on the cellular processes implicating environmental toxins via the ER Hyperstress/Cellular Detoxification Deficiency Model of ASD, see [10].
We can no longer afford to study G alone, E alone, and ignore G x E in ASD and other neurodevelopmental disorders. Future genetic studies should examine risk of environmental susceptibility in ASD, and include all sources of toxins.
[1] https://molecularautism.biomedcentral.com/articles/10.1186/s13229-016-0110-z
[2] https://www.omicsonline.org/peer-reviewed/pautism-is-an-acquired-cellular-detoxification-deficiency-syndrome-with-heterogeneous-genetic-predispositionp-99314.html
[3] https://www.sciencedirect.com/science/article/pii/S0946672X17300950
[4] https://www.ncbi.nlm.nih.gov/pubmed/29307441
[5] https://www.cdc.gov/vaccines/pregnancy/pregnant-women/index.html
[6] https://www.nature.com/articles/srep26185
[7] https://www.sciencedirect.com/science/article/pii/S0946672X17308763
[8] https://www.ncbi.nlm.nih.gov/pubmed/20920818
[9] https://www.cdc.gov/media/releases/2018/p0426-autism-prevalence.html
[10] http://ipaknowledge.org/ASD-Causality-Model.php
This is one interpretation, but it is incorrect on two counts. The majority of heritable studies actually show similar levels of contributed risk from genes and the environment, including those that did not measure any environmental factors. Since no studies have examined the role of environmental factors and genetic factors in the same populations, the significance of risk from genetic x environment interaction has never been measured. Further attributing risk to genetics alone in heritability studies likely conflates heritable variation in brain attributes that are also heritable in the neurotypical population, and the overall genetic contribution is likely exaggerated. This would include neurological differences whose effects are altered in the presence of ubiquitous environmental toxins. By analogy, if everyone smoked, lung cancer would appear to be genetic.
Some of the heritability appears to be due to heritability of susceptibility to environmental toxins. The list of environmental toxins implicated by studies to date are numerous and varied, pointing to a cellular detoxification deficiency syndrome with altered metal detoxification, and, importantly, increased ER stress response and altered Unfolded Protein Response outcomes[1]. Autistics' have altered blood/brain and intestinal barrier functions[2], meaning they belong to a subset of people who cannot handle toxins from various sources as well as others.
We recently found that the FDA and the HHS both erred in their determination that the amount of aluminum in vaccines is 'safe' in the first six months of life [3]. Masson et al. (2018) similarly found flaws and unwarranted assumptions in two key studies[4]. "Genetic" interpretations of findings of signs of neurological difference in ASD prior to birth ignore the CDC's policy shift to promote vaccination during pregnancy[5]. This practice, which now involves thimerosal-containing flu vaccines, TdaP (primarily for pertussis), and others as needed [5] is conducted contra FDA approval and, in the case of pertussis, against product labeling. If mothers of children at risk of ASD also have cellular detoxification deficiency, the "genetic" aspect of ASD likely involves (partly) environmental susceptibility genes. Uptake of toxins from diet via a compromised gut lining, likely due to activated enteric microglia, will compound the effects of other sources of toxins.
The environmental susceptibility variation contributing ASD risk can include variation in protein-coding genes that alters their intrinsic disorder, making them more difficult to fold in the endoplasmic reticulum (ER), leading to genetically induced ER stress. Importantly, the protein or protein(s) involved can have any cellular function. Both thimerosal and aluminum cause ER stress, mitochondrial dysfunction, and impaired Golgi functions, all essential for proper cellular detoxification[1]. This means ASD individuals will tend to acquire a variety of types of toxins - and this has been observed, with levels predictive of severity of behavior [6].
The combined effects of genetic ER stress and environmentally induced ER stress is called ER Hyperstress[1], favoring ER overload (over reduction in transcription or translation), forcing the UPR to conclude via apoptosis independent of p53, release of cytokines, and re-distribution of toxins bound to cellular debris, which are picked up by macrophages which locate these metals to the periphery of the brain. Aluminum has been found in the brain of people with ASD[7].
Multiple chemical sensitivity is commonly reported in people with autism and is on the increase throughout the general population[8]. With ASD now estimated at 1 in 59, and 1 in 37 in boys [9], there is simply no plausible mechanism for a "mostly genetic" condition to appear within 1-1.5 generations,
For more citations on the cellular processes implicating environmental toxins via the ER Hyperstress/Cellular Detoxification Deficiency Model of ASD, see [10].
We can no longer afford to study G alone, E alone, and ignore G x E in ASD and other neurodevelopmental disorders. Future genetic studies should examine risk of environmental susceptibility in ASD, and include all sources of toxins.
[1] https://molecularautism.biomedcentral.com/articles/10.1186/s13229-016-0110-z
[2] https://www.omicsonline.org/peer-reviewed/pautism-is-an-acquired-cellular-detoxification-deficiency-syndrome-with-heterogeneous-genetic-predispositionp-99314.html
[3] https://www.sciencedirect.com/science/article/pii/S0946672X17300950
[4] https://www.ncbi.nlm.nih.gov/pubmed/29307441
[5] https://www.cdc.gov/vaccines/pregnancy/pregnant-women/index.html
[6] https://www.nature.com/articles/srep26185
[7] https://www.sciencedirect.com/science/article/pii/S0946672X17308763
[8] https://www.ncbi.nlm.nih.gov/pubmed/20920818
[9] https://www.cdc.gov/media/releases/2018/p0426-autism-prevalence.html
[10] http://ipaknowledge.org/ASD-Causality-Model.php