Genetic and endocrine findings in a 31-year-old 45,X/46,Xdel(Y)(q12) male.

This report describes genetic, endocrine, and histological findings in a 31-yr-old 45,X/46,Xdel(Y)(q12) male with gynecomastia and azoospermia. A preponderance of 45,X cells was found in all tissues studied. Endocrine data suggested an abnormal Leydig cell-pituitary gonadotroph axis, although the basal testosterone level and the response to short term administration of hCG were normal. Testicular histology showed Leydig cell hyperplasia and seminiferous tubule atrophy. These findings are compared to 17 similar cases in the literature. A characteristic of all these cases is a morphologically abnormal Y-chromosome, which probably results in the 45,X cell line. The masculinizing genes on the remaining Y-chromosomes are functionally intact and promote a male phenotype in infancy and adolescence. Azoospermia is usually present, and gynecomastia or hypogonadism occurs later in life. Comparison with other nonmasculinized 45,X/46,XY cases supports existing theories regarding the function of the various segments of the Y-chromosome.