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

Abstract

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.