A 33-year-old man had azoospermia and tubular atrophy as in the Klinefelter syndrome but short stature. He had a 46,X,t(X/Y) (Xqter lead to p22.3::Yp11 lead to Yqter) translocation and was H-Y antigen-positive. This excludes one of the genes controlling H-Y antigen from the terminal portion of the short arm of the Y chromosome. This case and the two similar ones in the literature indicate that the proximal Yp portion is required for the differentiation of a male gonad. The pattern of X inactivation was random in the patient's fibroblasts, whereas in the lymphocytes the translocated chromosome was preferentially inactivated; comparison with other cases shows that the quantity of Y chromosome material involved in these translocations does not influence the X inactivation patterns. In the three cases with this dicentric translocation the X chromosome centromere is consistently the active one. Our case indicates that the choice of which centromere is inactivated is independent of the replication pattern of the X chromosome. Our patient and a few other relevant cases from the literature confirm that factors controlling height are located on the distal portion of Xp and of Yp.

A 7-month-old child with normal male external genitalia and normal, descended testicles had a 45,X karyotype in blood, skin, and testis cultures. He was mentally retarded and had a variety of bone alterations indicating disturbances of growth and ossifications. Dermatoglyphic patterns have several of the characteristics found in the 45,X female subjects with Turner's syndrome. This seems to be the first case of an "XO male" with normal external genitalia. We postulate

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