Identical twins discordant for the "rudimentary testes" syndrome

A 20-year-old man was found to have rudimentary testes, microphallus and minimal evidence of sexual maturation, along with low serum testosterone and high serum gonadotropin levels, consistent with the syndrome of rudimentary testes and microphallus. His identical twin brother was unaffected, confirming that this unusual congenital disorder does not have a genetic basis in all cases.