Breathing efforts and the success of such are affected by genetic factors. Factors that decrease the size and/or increase the floppiness of the upper airway increase the individual’s risk of obstructive sleep apnea. Many genetic syndromes can therefore affect breathing during sleep, through anatomic abnormalities affecting central respiratory control, or anatomic and physiologic factors affecting the properties of the upper airway. Congenital disorders affecting breathing during sleep can be classified into 1 of 4 categories: micrognathia, midface hypoplasia, disorders of neuromuscular control, and miscellaneous disorders. Some of the more common syndromes with these features are reviewed here.