[Epidemiology. Risk factors and genetic influence].
Epidemiological studies of sleep-disordered breathing in broad population samples are scarce. Nevertheless, currently available data indicate that habitual snoring is present in 7.45 % (95 % CI: 5.75-9.61) of the child population. Approximately 10 % of habitual snorers develop sleep apnea. However, in children with associated comorbidity (obesity, asthma…) or clinical symptoms of sleep-disordered breathing, the association between snoring and sleep apnea is significantly increased. The prevalence of sleep apnea according to parents' or guardians' observation of apnea episodes is 0.2-4 %. When the diagnosis is based on questionnaires administered directly to parents, the prevalence increases to 4-11 %. If diagnosis is made by objective means, the prevalence ranges from 1-4 %. Obesity is currently a major risk factor. In obese children, the prevalence of sleep apnea oscillates between 4.69 % and 6.6 % and consequently screening of sleep-disordered breathing in obese patients with or without suggestive symptoms should be routine. Genetic factors strongly influence sleep-disordered breathing and seem to account for 35-40 % of the variance in this disorder, although their precise role has yet to be clarified. Genetic study opens up an important gateway in the future medical approach to sleep-disordered breathing.