Phenotypic Male With Mosaic Sex Chromosomes

SEVERAL DIFFERENT KARYOTYPES, some with mosaicism, have now been demonstrated in cells from patients with the disorder of male sex differentiation known as Klinefelter's syndrome. The XXY sex chromosome pattern was the first aberration described in Klinefelter's syndrome 1 and has been the most frequent finding in cases subsequently studied. It has been suggested that those patients with Klinefelter's syndrome, but with karyotypes other than XXY, be considered as variants. 2 The sex chromosome pattern in the variants thus far recognized include XXXY, XXXXY, XXYY, XXXYY, and the mosaic karyotypes of XX/XXY, XY/XXY, XY/XXXY, XXXY/XXXXY, XX/XXY/ XXYYY. Although patients having these different karyotypes cannot be distinguished unequivocally on clinical grounds alone, it appears that the severity of mental retardation and disturbances of sex differentiation increase as the number of extra X chromosomes increases. This case of Klinefelter's syndrome is reported to provide clinical and cytological findings of a patient with