17-beta hydroxysteroid dehydrogenase III deficiency, also known as 17-KSR deficiency or male pseudohermaphroditism with gynecomastia (MPH), is as rare inborn error of metabolism (IEM) and autosomal recessive disorder of the androgen and estrogen metabolism pathway. It is caused by a mutation in the HSD17B3 gene, which encodes the enzyme testosterone 17-beta-dehydrogenase 3, which is responsible for catalyzing the reversible formation of androstenedione from testosterone. This leads to an accumulation of androstenedione and dehydroepiandrosterone in the body, as well as a lack of testosterone produced. 17-KSR deficiency is characterized by an absence of testosterone in the testis until puberty, where testosterone is produced outside of the gonads. Symptoms include infertility and external female genitalia until puberty, when secondary male sex characteristics occur, as well as gynecomastia. Due to this, many individuals with this disorder are raised as female despite being genetically male, until puberty. Treatment can include removal of testes before puberty, preventing any masculinization at puberty, as well as surgical treatment of genitalia. However, there is no known treatment for restoring the fertility of affected individuals. It is estimated that 17-KSR deficiency affects 1 in 150,000 individuals in The Netherlands, without much information for the rest of the world.

17-beta Hydroxysteroid Dehydrogenase III Deficiency References