Parental age and the origin of extra chromosome 21 in Down syndrome.
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.
Jyothy
A
A
Institute of Genetics and Hospital for Genetic Diseases, Osmania University, Begumpet, Hyderabad, India. ksdkumar@rediffmail.com
Kumar
K S
KS
Mallikarjuna
G N
GN
Babu Rao
V
V
Uma Devi
B
B
Sujatha
M
M
Reddy
P P
PP
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