Testosterone 17-beta-dehydrogenase 3 (HSD17B3) is involved in the pathway testosterone biosynthesis. It catalyses the conversion of the androstenedione to testosterone, which is responsible for the normal fetal development of male genitalia. It is predominantly expressed in the testes and utilizes NADPH as a cofactor. Mutations in the HSD17B3 gene cause 17beta-hydroxysteroid dehydrogenase type 3 (17beta-HSD3) deficiency cause 46, XY Disorders of Sex Development (46, XY DSD) [].