Congenital hypothyroidism (CH) is a rare disease that affects 1 in 3500 newborn. This condition is detected consistently since the late 1970s in France, which has led to early care and a significant improvement in prognosis and intellectual stature of these children. However neurodevelopmental disorders persist in 10-15% of cases. More associated diseases have been reported in approximately 10% of cases. These observations are in most cases poorly understood. The family nature of the CH is now well recognized and a dozen genes involved up to now. However, in the majority of cases (HC not due to a disorder of the organification of iodine), few mutations have been found in the reported number of patients (5-10%), suggesting the involvement of other genes. Some of the genes have been implicated in particular specific syndromic forms but many pathological associations remain unexplained. Also, a more complete genetic elucidation of CH would enable a better understanding of its etiology and thus its risk of familial recurrence (frequently asked questions by parents of children with CH) and secondly the presence of associated pathologies.