[Ondine syndrome: myth meets reality].

Congenital central alveolar hypoventilation (CCAH), previously called Ondine Syndrome, is a rare disease, with an incidence of 1/200000 births and a prevalence of 1/500000. It is a defect in the central control of ventilation, not explained by muscular, neurological, cardiological, or pulmonary abnormalities. Early diagnosis is important to avoid episodes of hypoxia and hypercapnia, which overshadow the prognosis. The definitive diagnosis is made by determining mutations in the PHOX2B gene on chromosome 4p13. Two members of the same family are presented, mother and daughter with different clinical presentations. CCAH is a diagnostic challenge. Suspected or confirmed cases should be evaluated in reference centers.