17β-Hydroxysteroid dehydrogenases (17β-HSD, HSD17B), also 17-ketosteroid reductases (17-KSR), are a group of alcohol oxidoreductases which catalyze the reduction of 17-ketosteroids and the dehydrogenation of 17β-hydroxysteroids in steroidogenesis and steroid metabolism. This includes interconversion of DHEA and androstenediol, androstenedione and testosterone, and estrone and estradiol. The major reactions catalyzed by 17β-HSD (e.g., the conversion of androstenedione to testosterone) are in fact hydrogenation (reduction) rather than dehydrogenation (oxidation) reactions.

Reactions

17β-HSDs have been known to catalyze the following redox reactions of sex steroids:

Activity distribution

Genes

Genes coding for 17β-HSD include: At least 7 of the 14 isoforms of 17β-HSD are involved in interconversion of 17-ketosteroids and 17β-hydroxysteroids.

Overview

Clinical significance

Mutations in HSD17B3 are responsible for 17β-HSD type III deficiency. Inhibitors of 17β-HSD type II are of interest for the potential treatment of osteoporosis. Some inhibitors of 17β-HSD type I have been identified, for example esters of cinnamic acid and various flavones (e.g. fisetin).