Inherited congenital normofunctional testicular hyperplasia and mental deficiency.

Four 46,XY siblings with congenital bilateral megalorchidia, marcogenitosomia, and severe mental deficiency were investigated. The testicular size was significantly larger than age-matched normal males. A normal hypothalamic-pituitary gonadotropin function was demonstrated by the finding of normal levels of luteinizing and follicle-stimulating hormones in blood samples drawn at frequent intervals and by normal responses to gonadotropin-releasing hormone and testosterone administration. A normal testicular function was shown by the finding of normal (a) plasma testosterone and estradiol levels, (b) gonadal response to human chorionic gonadotropin, (c) sperm analysis, and (d) morphology and cell architecture of the testes. Adrenal function was found to be within normal limits. These results demonstrated the existence of normofunctional testicular hyperplasia. The family studies suggested that this distinct congenital disorders is inherited as an X-linked recessive trait.