Fertile eunuch syndrome is a form of idiopathic hypogonadotropic hypogonadism in males. It is characterized by eunuchoid features associated with normal or low-normal sized testes, presence of active spermatogenesis despite the absence or scarcity of Leydig cells, and androgenic response (clinical or chemical or both) to administered human chorionic gonadotropin. In this disease, the levels of testosterone and follicle-stimulating hormone (FSH) are inadequate to induce spermatogenesis and the development of secondary sexual characteristics. Mutations in the beta subunit of luteinizing hormone gene have been identified from patients of this disease.
