IS THE SLEEP-APNEA HYPOPNEA SYNDROME INHERITED

Background-The aetiology of the sleep apnoea/hypopnoea syndrome (SAHS) is unclear in many patients. Snoring, a prerequisite for SAHS, runs i n families. A study was carried out to determine whether there is an i ncreased frequency of irregular breathing during sleep in relatives of patients with SAHS. Methods-A prospective study was performed of firs t degree relatives of 20 consecutive non-obese (BMI <30 kg/m2) patient s with SAHS. Questionnaires on SAHS symptoms were sent to all first or der relatives and those living within 150 miles of Edinburgh were invi ted for overnight monitoring of their breathing, sleep, and oxygenatio n patterns in the sleep laboratory. Results-Ten of the 40 relatives ha d more than 15 apnoeas + hypopnoeas/hour of sleep, and eight had more than five 4% desaturations/hour. These frequencies of irregular breath ing and desaturation are significantly higher than in the British popu lation. Cephalometric studies showed no skeletal abnormality but an in creased uvular width was found in the affected relatives. Conclusions- There is an increased frequency of abnormal breathing during sleep in relatives of non-obese patients with SAHS.