Mutations affecting gonadotropin secretion and action.

A number of mutations are known to disturb the development and function of the hypothalamic-pituitary-gonadal axis. They affect hypothalamic-pituitary-gonadal function at multiple levels, from the migration of gonadotropin releasing hormone neurons to the hypothalamus right through to gonadotropin action in the ovary and testis. Most of the mutations are inactivating, causing various forms of hypogonadism. Exceptions are the activating mutations of the luteinizing hormone receptor, causing male-limited gonadotropin-independent precocious puberty. The human mutations and genetically modified animal models have clarified the molecular pathogenesis of hypogonadism and such disorders can now be diagnosed using molecular biological techniques, enabling selection of specific treatments and appropriate counselling of patients and their families.