Summary
The lymphocyte chromosomes of trisomy 21 Down syndrome patients and their parents in a random series of 374 families were analyzed, the objective being the identification of parental mosaicism. The numbers of parents in whom at least two trisomy 21 cells were detected were seven mothers and three fathers, a frequency of 2.7% of families. Confirmation of mosaicism was by identification of parental transmission of the extra chromosome to the progeny, by repeat chromosome analysis, and/or by the presence of more than one affected child. If to these are added six others in whom only one trisomic cell was detected, but with no other supporting evidence, the frequency could be as high as 4.3%. Differences in parental age at the birth of Down syndrome progeny may be accounted for by differences in frequencies of mosaicism in germ cells and somatic tissue. Mosaicism was found more frequently in the mothers than in the fathers, but more data are required for confirmation of a real difference.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Alfi OS, Chang R, Azen SP (1980) Evidence for genetic control of non-disjunction in man. Am J Hum Genet 32:477–483
Dallaire L, Fraser FC (1964) Two unusual cases of familial mongolism. Can J Genet Cytol 4:540–547
Golden WL (1981) Reproductive histories in a Norwegian twin population: Evaluation of the maternal effect in early spontaneous abortion. Acta Genet Med Gemellol (Roma) 30:91–165
Harris DJ, Begleiter ML, Chamberlin J, Hankins L, Magenis RE (1982) Parental trisomy 21 mosaicism. Am J Hum Genet 34:125–133
Hook EB (1977) Exclusion of chromosomal mosaicism: Tables of 90%, 95% and 99% confidence limits and comments on use. Am J Hum Genet 29:94–97
Hsu LYF, Gertner M, Leiter E, Hirschhorn K (1971) Paternal trisomy 21 mosaicism and Down's syndrome. Am J Hum Genet 23:592–601
Penrose LS (1934) The relative aetiological importance of birth order and maternal age in mongolism. Proc R Soc Lond [Biol] 115:431–450
Penrose LS (1965) Dermatoglyphics in mosaic mongolism and allied conditions. In: Geerts SJ (ed) Genetics today, vol 3. Pergamon Press, Oxford, p 973
Yokoyama S, Reich T, Morgan K (1981) Inbreeding and the genetic control of nondisjunction. Hum Genet 59:125–128
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Uchida, I.A., Freeman, V.C.P. Trisomy 21 Down syndrome. Hum Genet 70, 246–248 (1985). https://doi.org/10.1007/BF00273450
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00273450