Male to female ratio (sex ratio, SR) for 1,329 liveborns with Down syndrome and for 178,160 newborns from the general population of St. Petersburg, Russia was determined as a function of a mother age. Male prevalence (an overall SR of 1.24) was found in children with all trisomy 21 variants except the cases with mosaicism (the ratio of 0.88). The most expressed male predominance was determined in children of mothers aged 20-24 years, where SR was 1.73 in the total group (p = 0.00003) and 1.61 in the cases with free trisomy (p = 0.0007). Some hypotheses concerning the male accumulation in this group are discussed including a suggestion that the SR deviations from the population value 1.06 might be due to different contribution of paternal chromosomal non-disjunction during spermatogenesis.

Adult↗

PubMedDate not supplied

[Reproductive behavior and Down syndrome].

Coital rates and contraception practice were investigated in mothers of 160 newborns with Down syndrome (DS) in comparison with the same aged (+/- 1 year) mothers of 160 healthy newborns. A considerable lowering of sexual activity is typical for parents, especially young ones, of children with DS. No relationship between parental sexual behavior and maternal hormonal dysfunction was found. Study on children sex ratio (SR) in relation to parental sexual activity revealed that the prevalence of boys in the DS children was due to the excess of boys (SR = 1.85) in the small group of children from sexually active couples. These data are discussed as evidence of association of a high coital rate with chromosome malsegregation in spermatogenesis.

Coitus↗

PubMedDate not supplied

[Multiple chromosome aberrations in 3 generations of a family and Down's syndrome resulting from partial trisomy of chromosome 21 (q21--q22)].

Two balanced translocations (1; 16) (q22; q11) and t(21; 22) (q21; p11), partial inversion of chromosome 9 and variant 16gh + were detected in the family of the child with Down's syndrome. The proband clinical picture was due to trisomy of the distal region of the long arm of chromosome 21 (q21----q22). Proband's karyotype was 46, XY, --22, +der(22), t(21; 22)mat, inv(9). Carriers of variant 16gh+ had a normal phenotype and a normal reproductive function. The relation is discussed of the balanced translocations and C-heterochromatin to the development of following chromosomal aberrations. A probability prediction of the progeny is given. It is advisable to make a prenatal diagnosis of the fetal chromosome set for each subsequent pregnancy.

Adult↗

PubMedDate not supplied

[Structural chromosomal reorganizations and mosaicism in the parents of children with Down's syndrome].

As to the authors' data 73% of women who gave birth to children with Down's syndrome (DS) (191 out of 231) were younger than 35 years. In this "young" group 191 couples were examined caryologically, 9 individuals having balanced translocations and 4 persons having mosaicism with a little trisomic clone were revealed. Mean ages of these parents are 24.3 for women and 32.5 for men. The rate of chromosome aberrations is 1.95% that is 8 times higher than in general population of newborns. 0.85% of examinees had heavy detectable mosaicism. Hence, no less than 5.6% of families with DS child, that are not subjected to a prenatal diagnostics because of young age, have different chromosome aberrations causing high risk of birth of an abnormal child.

Adolescent↗