Gonadal dysgenesis and ?-chromosome abnormalities

Fifteen subjects with chromosome mosaics were investigated: in ten of them a chromosome pattern 45,X/46,X,i dic(Yp) was found, in four 45,X/46,X,i dic(Yq), in one 45,X/46,X,Yq+.; the ratio of the two cell types varied between patients and between different tissues. The phenotype of patients ranged from female with some Turner's syndrome stigmata, to infants with ambiguous external genitalia, to azospermic male. Most patients presented short or very short stature. Laparatomy and hystologic studies revealed hypoplasic or dysgenetic or ever normal testes and streak gonads variously combined; four patients were tested for H-Y antigen anc found to be positive-reduced. No correlation was demonstrated between clinical data and chromosomal pattern. Phenotypic feature of mosaics with structurally abnormal Y-chromosomes are not different from feature found in 45,X/46,XY patients; probably no genetically active portion of Y is lost. The different proportion of 45,X cells in various tissues possibly has the greatest influence on the phenotype of these subjects.This investigation was performed in collaboration with the Institute of General Biology and Genetics, University of Pavia.