17-β-hydroxysteroid dehydrogenase type 3 deficiency in three adult Iranian siblings

17-β-hydroxysteroid dehydrogenase type 3 (17-β-HSD 3) deficiency is an autosomal recessive form of 46,XY disorder of sex development (DSD). To date, a total of 27 HSD17B3 gene mutations have been described in 46,XY patients exhibiting different phenotypes at birth and virilization at puberty, sometimes in association with gynecomastia. Herein, we investigate the 46,XY DSD in an Iranian family consisting of 7 siblings, 3 of which are affected and virilized at puberty. We clinically characterized these patients and performed direct DNA sequencing of the steroid 5-α-reductase type 2 (SRD5A2) and the HSD17B3 gene, respectively. We identified a homozygous mutation in the HSD17B3 gene (R80W; c.238C>G) in all affected siblings. No mutation was detected in the SRD5A2 gene. The detected mutation in the HSD17B3 gene was previously described in a newborn child, who died from other congenital malformations, and in a 12-year-old girl. Hence, our report adds novel value to the phenotype classification of 17-β-HSD 3 deficiency.