Human 17-ketosteroids ELISA kit

Four isozymes of steroid 17 beta-hydroxysteroid dehydrogenase (17 beta HSD) encoded by different loci catalyze the reversible conversion of androstenedione to testosterone and that of estrone to estradiol. The 17 beta HSD type 3 (17 beta HSD3) isozyme is encoded by the 17 beta HSD3 gene on chromosome 9q22 and expressed only in testes. Inherited defects in the 17 beta HSD3 isozyme cause a form of male pseudohermaphroditism that is rare within the general population, but frequent among a highly inbred Arab population in the Gaza strip. A point mutation in exon 3, codon 80 of the 17 beta HSD3 gene, R80Q, caused by a single base substitution from CGG to CAG was identified in both alleles of 24 individuals from 9 extended Arab families from Gaza, Jerusalem, and Lod-Ramle. Twenty-one homozygotes were male pseudohermaphrodites (46,XY) with testicular 17 beta HSD3 deficiency, born with either female-looking external genitalia or various degrees of genital ambiguity. If not reassigned in infancy, they were reared as females until puberty, when marked virilization occurred, often leading to the spontaneous adoption of a male gender role. In contrast, the 3 homozygote females (46,XX) were asymptomatic, had normal internal and external genitalia and normal sexual development, and revealed no biochemical evidence of 17 beta HSD3 deficiency. The molecular pattern in these families is compatible with an autosomal recessive mode of inheritance that is sex dependent.

The enzyme 17 beta-hydroxysteroid dehydrogenase (17 beta HSD) interconverts 17-ketosteroids and 17 beta-hydroxysteroids. Five isoforms of the enzyme have been identified in the human, two of which (types 1 and 3) have been shown to catalyse the reduction reaction preferentially. The cDNA encoding mouse 17 beta HSD type 3 was isolated from testis cDNA using the RACE technique and primers based on the human sequence. The mouse protein is 305 amino acids in length which is five short of the human protein with four of these amino acids missing at the N-terminus. The predicted amino acid sequence is 72.5% identical and 94.8% similar to the human sequence. Tissue distribution of mRNA encoding both types 1 and 3 17 beta HSD was studied using reverse transcription and the polymerase chain reaction (RT-PCR). Highest levels of type 1 mRNA were found in the ovary whereas highest levels of type 3 were in the testis. All other tissues tested contained mRNA encoding both isoforms of the enzyme although levels were markedly lower than in the gonads. Copyright (C) 1997 Published by Elsevier Science Ltd.