Familial adult onset primary alveolar hypoventilation syndrome

A cll-year-old man fell into type II respiratory failure after catching a c old, and became dependent on a respirator, Chest radiography showed no abno rmalities and the hyperventilation test showed improved arterial blood gas findings. His sleep study showed marked nocturnal desaturation due to hypop nea and apnea with a decrease of thoracic and abdominal movement during sle ep, Therefore, we diagnosed hint as primary alveolar hypoventilation syndro me (PAH), Seven years previously, his 2-year elder sister had suffered from similar respiratory failure during her second pregnancy and had been diagn osed as PAH, While myopathy was suspected in both cases, attenuation of mus cle strength was slight and it appeared not to be the main cause of alveola r hypoventilation, Since medication was not effective in each case, they un derwent non-invasive positive pressure ventilation (NIPPV). While sustained mild hypercapnia remained during the daytime, it improved their respirator y failure, To our knowledge, this is the first study of familial adult onse t PAH.