Lack of Methylation Changes in GJB2 and RB1 Non-coding Regions of Cochlear Implant Patients with Sensorineural Hearing Loss

Angelo Augusto Sumalde; Ivana Yang; Talitha Karisse Yarza; Celina Ann Tobias-Grasso; Ma. Leah Tantoco; Elizabeth Davidson; Abner Chan; Mahshid Azamian; Teresa Luisa Cruz; Seema Lalani; Maria Rina Reyes-Quintos; Eva Maria Cutiongco-de la Paz; Regie Lyn Santos-Cortez; Charlotte  Chiong

doi:10.47895/amp.v57i9.5200

Angelo Augusto M. Sumalde, MD, PhD College of Medicine, University of the Philippines Manila, Manila, Philippines; Department of Otolaryngology – Head and Neck Surgery, School of Medicine, University of Colorado Anschutz Medical Campus (CU-AMC), Aurora, Colorado, USA; Department of Otolaryngology-Head and Neck Surgery, Philippine General Hospital, University of the Philippines Manila, Manila, Philippines
Ivana V. Yang, PhD Department of Medicine, School of Medicine, University of Colorado Anschutz Medical Campus (CU-AMC), Aurora, Colorado, USA
Talitha Karisse L. Yarza, MClinAud Philippine National Ear Institute, National Institutes of Health, University of the Philippines Manila, Manila, Philippines; Newborn Hearing Screening Reference Center, National Institutes of Health, University of the Philippines Manila, Manila, Philippines
Celina Ann M. Tobias-Grasso, BSN, AuD MED-EL, Innsbruck, Austria
Ma. Leah C. Tantoco, MD, MClinAud Department of Otolaryngology-Head and Neck Surgery, Philippine General Hospital, University of the Philippines Manila, Manila, Philippines; Philippine National Ear Institute, National Institutes of Health, University of the Philippines Manila, Manila, Philippines; Newborn Hearing Screening Reference Center, National Institutes of Health, University of the Philippines Manila, Manila, Philippines
Elizabeth Davidson Department of Medicine, School of Medicine, University of Colorado Anschutz Medical Campus (CU-AMC), Aurora, Colorado, USA
Abner L. Chan, MD College of Medicine, University of the Philippines Manila, Manila, Philippines; Department of Otolaryngology-Head and Neck Surgery, Philippine General Hospital, University of the Philippines Manila, Manila, Philippines
Mahshid S. Azamian, MD, MPH, CCRP Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
Teresa Luisa G. Cruz, MD, MHPEd College of Medicine, University of the Philippines Manila, Manila, Philippines; Department of Otolaryngology-Head and Neck Surgery, Philippine General Hospital, University of the Philippines Manila, Manila, Philippines
Seema R. Lalani, MD Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
Maria Rina T. Reyes-Quintos, MD, MClinAud, PhD Department of Otolaryngology-Head and Neck Surgery, Philippine General Hospital, University of the Philippines Manila, Manila, Philippines; Philippine National Ear Institute, National Institutes of Health, University of the Philippines Manila, Manila, Philippines; Newborn Hearing Screening Reference Center, National Institutes of Health, University of the Philippines Manila, Manila, Philippines
Eva Maria Cutiongco-de la Paz, MD National Institutes of Health, University of the Philippines Manila, Manila, Philippines; Philippine Genome Center, UP Diliman Campus, Quezon City, Philippines
Regie Lyn P. Santos-Cortez, MD, PhD Department of Otolaryngology – Head and Neck Surgery, School of Medicine, University of Colorado Anschutz Medical Campus (CU-AMC), Aurora, Colorado, USA https://orcid.org/0000-0002-9958-2535
Charlotte M. Chiong, MD, PhD 1 College of Medicine, University of the Philippines Manila, Manila, Philippines; Department of Otolaryngology-Head and Neck Surgery, Philippine General Hospital, University of the Philippines Manila, Manila, Philippines; Philippine National Ear Institute, National Institutes of Health, University of the Philippines Manila, Manila, Philippines; Newborn Hearing Screening Reference Center, National Institutes of Health, University of the Philippines Manila, Manila, Philippines

DOI: https://doi.org/10.47895/amp.v57i9.5200

Keywords: GJB2, hearing loss, methylation, qMSP, RB1, sensorineural

Abstract

Objective. Recent advances in epigenetic studies continue to reveal novel mechanisms of gene regulation and control, however little is known on the role of epigenetics in sensorineural hearing loss (SNHL) in humans. We aimed to investigate the methylation patterns of two regions, one in RB1 and another in GJB2 in Filipino patients with SNHL compared to hearing control individuals.

Methods. We investigated an RB1 promoter region that was previously identified as differentially methylated in children with SNHL and lead exposure. Additionally, we investigated a sequence in an enhancer-like region within GJB2 that contains four CpGs in close proximity. Bisulfite conversion was performed on salivary DNA samples from 15 children with SNHL and 45 unrelated ethnically-matched individuals. We then performed methylation-specific real-time PCR analysis (qMSP) using TaqMan® probes to determine percentage methylation of the two regions.

Results. Using qMSP, both our cases and controls had zero methylation at the targeted GJB2 and RB1 regions.

Conclusion. Our study showed no changes in methylation at the selected CpG regions in RB1 and GJB2 in the two comparison groups with or without SNHL. This may be due to a lack of environmental exposures to these target regions. Other epigenetic marks may be present around these regions as well as those of other HL-associated genes.