7 ICHTHYOSIS(I) AND HYPOGONADISM(H) IN TWO BROTHERS WITH DELETION OF THE SHORT ARM OF THE X-CHROMOSOME

Abstract

Two brothers aged 9.5(N) and 17 years(J) respectively, underwent bilateral orcheopexy at the age of 4 years and were recently examined for H. They were healthy, tall, of normal intelligence and they presented skin lesions of I. The testes were small (1m) in N bilaterally, and in J R:1ml, L:3-4ml). J. had received testosterone for 1 year and had Tanner III pubic hair. There was no response of serum testosterone to HCG and no appreciable response of LH and FSH to IV LHRH. Serum DHEAS values were 518 in N and 3700ng/ml in J. STS activity in WBC was 0 pmols/hr/mg protein in both subjects (control:24.9). Flow cytometry showed the X chromosome to be 2-3% smaller than normal, indicating a large deletion of about 5 million base pairs. No hybridization to the probe GMGX9 (DXS 237) was found, indicating steroid sulfatase (STS) gene deletion. There was hybridization to the probe dic 56 (DXS 143), which is proximal to STS. This puts a proximal limit on the extent of the deletion. They were heterozygous for the probe pl9b at the MIC2X locus which puts a distal limit on the deletion. Hence, in these two brothers with I and H, a large deletion of the short arm of the X chromosome was disclosed which included the STS locus, the closely linked locus DXS 237 and the gene for hypogonadism, findings which offer the opportunity for speculations on the locus of control of normal testicular development and function.