Indeed, full penetrance of megacolon in Ret+/-::Ednrbs/s males was correlated with a mean length of the ganglionated region clearly beneath the threshold (59% of colon length) whereas partial penetrance of megacolon in Ret+/-::Ednrbs/s females was correlated with a mean length of the ganglionated region much closer to the threshold (72%) [14]. The gene discussed is RET; the disease is Aganglionic megacolon.