These data suggest that it is not the sharing of HLA-A and HLA-B antigens between the parents or between the parent who was the origin of the nondisjunction and the D.S. child that is related either to the occurrence of trisomy 21 zygotes or to prenatal survival of affected embryos and fetuses.
As the HLA system could play a role in the in utero selection process against abnormal fetuses, HLA-A and -B antigens were evidenced in 30 children with trisomy 21 and in their parents, using a standard microlymphocytotoxicity test.
The data suggest that sharing of parental HLA-A and B antigens may be related either to the occurrence of trisomy 21 zygotes or to prenatal survival of affected embryos and fetuses.