title: Parental age and the origin of extra chromosome 21 in Down syndrome.
abstract: We present a report of the parental ages (n = 865) and parental origin of meiotic nondisjunction (n = 236) that are likely to show a predisposition in the etiology of Down syndrome (DS). Chromosomal analysis, performed over a 20-year period, on 1,001 Down syndrome subjects, revealed pure trisomy 21 karyotype in 880 subjects (87.92%), mosaic trisomy karyotype in 77 (7.69%), and translocation karyotype in 44 (4.39%). The mean maternal age was found to be 30.34 years, and mean paternal age was 31.04 years. Nondisjunctional error was 79.24% maternal and 20.76% paternal. The findings of the study revealed the significant contribution of advanced parental age and increased maternal meiotic nondisjunctional error to the origin of trisomy 21 Down syndrome.
authors.affiliation: Institute of Genetics and Hospital for Genetic Diseases, Osmania University, Begumpet, Hyderabad, India. ksdkumar@rediffmail.com
authors.forename: A
authors.initials: A
authors.lastname: Jyothy
authors.forename: K S
authors.initials: KS
authors.lastname: Kumar
authors.forename: G N
authors.initials: GN
authors.lastname: Mallikarjuna
authors.forename: V
authors.initials: V
authors.lastname: Babu Rao
authors.forename: B
authors.initials: B
authors.lastname: Uma Devi
authors.forename: M
authors.initials: M
authors.lastname: Sujatha
authors.forename: P P
authors.initials: PP
authors.lastname: Reddy
mesh_terms: D000328:Adult; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics*; D004314:Down Syndrome / Q000235:genetics*; D005260:Female; D006801:Humans; D007194:India; D008297:Male; D008423:Maternal Age; D008540:Meiosis / Q000235:genetics; D008875:Middle Aged; D009030:Mosaicism; D010331:Paternal Age; D014178:Translocation, Genetic