Rare phenotypic spectrum of 17β-hydroxysteroid dehydrogenase 3 deficiency: case series from infancy to adolescence

17β-Hydroxysteroid dehydrogenase 3 (17β-HSD3) deficiency is a rare 46XY disorder of sex development (DSD) of androgen biosynthesis. We aimed to describe the complexities in diagnosis, gender assignment, and the timing of irreversible surgical interventions in 17β-HSD3 deficiency.

We described three genetically confirmed cases of 46XY DSD due to 17β-HSD3 deficiency. All of them had female-appearing external genitalia, and the third case had well-developed breasts with clitoromegaly. The biochemical evaluation showed hCG-stimulated T/A ratios of 0.4 and 0.35 in Cases 1 and 2, respectively, and an unstimulated T/A ratio of 0.25 in Case 3. Molecular analysis revealed three different HSD17B3 variants: c.72C>A(p.Cys24Ter), c.764C>T(p.Ser255Leu), and c.607-1G>A(3'splice site) in the respective cases. Despite the female-appearing external genitalia in Case 1, the parents decided to rear the child as male, whereas Cases 2 and 3 retained a female gender identity. The first two cases were advised to have regular follow-up for gender dysphoria, while Case 3 was managed with injectable leuprolide depot and anti-androgens.

17β-HSD3 deficiency remains a challenging 46 XY DSD due to its clinical heterogeneity and diverse molecular spectrum. This report adds to current molecular knowledge by reporting two novel variants in the HSD17B3 gene.