title: HLA and trisomy 21. Confirmation of a trend of restricted HLA heterogeneity in parents of Down syndrome children.
abstract: 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 comparison group included 60 families among whom 39 had HLA typing for paternity exclusion and 21 had been previously selected for a segregation study. Both groups consisted of nonconsanguineous Caucasians from the same geographical area. The Down syndrome (DS) children did not show a significant association with a specific HLA antigen. However, six out of 30 couples having a DS child showed two antigens shared at the A and/or B locus, compared to seven out of 60 control couples. The shared parental antigens were not selectively inherited, and the proportion of homozygote children at one locus was lower for DS (5/30) than for controls (13/60). These findings demonstrate the same trend as previously published but need to be confirmed by other investigators. Perhaps a strong selective pressure in favor of heterozygotes contributes to a better survival rate, as suggested from histocompatibility studies in animals.
mesh_terms: D000328:Adult; D002648:Child; D004314:Down Syndrome / Q000235:genetics*; D005260:Female; D005819:Genetic Markers; D014644:Genetic Variation; D006680:HLA Antigens / Q000235:genetics*; D015234:HLA-A Antigens; D015235:HLA-B Antigens; D015797:HLA-B35 Antigen; D006579:Heterozygote; D006801:Humans; D008297:Male; D010290:Parents
chemical_list: D005819:Genetic Markers; D006680:HLA Antigens; D015234:HLA-A Antigens; D015235:HLA-B Antigens; D015797:HLA-B35 Antigen