Ichthyosis and hypogonadism in two brothers with deletion of the short arm of the X chromosome.

Two brothers were examined because of ichthyosis and hypogonadism. Their testes were small. There was no response of plasma testosterone to human chorionic gonadotropin and no response of plasma luteinizing hormone and follicle-stimulating hormone to intravenous luteinizing-hormone-releasing hormone. They both had hyposmia. Steroid sulfatase activity in white blood cells was zero. Flow cytometry and the use of special probes indicated that these two brothers had a large deletion of the short arm of the X chromosome which included the STS locus, the closely linked locus DXS237 and probably the gene for hypogonadism, findings which offer the opportunity for speculations on the locus of control of normal testicular development and function.