Respiratory patterns, awake and asleep, were investigated by polysomnography in 30 female patients with Rett syndrome and compared with 30 controls at the Eudowood Division of Pediatric Respiratory Sciences, Johns Hopkins University, and the Department of Neurology, Kennedy Krieger Institute, Baltimore, MD. The median age was 7 years (range, 1 to 32 years). During wakefulness, 67% of RS patients had a characteristic pattern of disordered breathing (hyperventilation followed by central apnea and desaturation). Breathing was normal during sleep. Arterial oxygen saturation during REM sleep was slightly lower in RS cf controls but within normal range. The authors postulate a normal brain-stem control of ventilation in RS and an abnormality or loss of the normal cortical influence on ventilation during wakefulness. The precise cause of the cortical dysfunction is unknown. 
COMMENT. Patients with Rett syndrome have normal respiration during non-REM sleep, slightly abnormal breathing in REM sleep, and markedly disturbed breathing during wakefulness. The hyperventilation is attributed to a cortical dysfunction.