Testicular agenesis

**Definition:** A rare 46,XY disorder of gonadal development characterized by congenital complete absence of testicular tissue in an individual with an otherwise male phenotype and normal karyotype. In addition, a small penis is a frequent finding in anorchid patients. Typical hormonal characteristics are elevated basal levels of gonadotropins (especially FSH (follicle-stimulating hormone), low concentration of testosterone, and lack of increase of plasma testosterone in response to hCG (human chorionic gonadotropin) administration. The GnRH (gonadotropin-releasing hormone) stimulation test induces a prolonged increase in FSH and LH (luteinizing hormone) levels.