Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is a common condition affecting ,2-4% of the middle-aged population. A hereditary component to the condition has long been recognised but its genetic basis has been difficult to elucidate. Progress in determining the genotype of OSAHS is hampered by the lack of a consistent definition of phenotype and the large environmental influences on its expression. ''Intermediate phenotypes'', such as craniofacial structure, obesity and upper airway control, have been utilised. Multiple gene polymorphisms have been explored in association with the latter, as well as with the sequelae of OSAHS, such as hypertension and increased insulin resistance. To date, two genome-wide scans have identified potential regions that may be of interest in further defining the intermediate phenotypes. The present paper focuses on human studies with an update of the most recent work in the area, including a short discussion on methods of genetic studies.
Background: Fractional exhaled nitric oxide (FeNO) is a marker of type-2 inflammation used both to support diagnosis of asthma and follow up asthma patients.The associations of FeNO with lung function decline and bronchodilator (BD) response have been studied only scarcely in large populations.Objectives: To study the association between FeNO and a) retrospective lung function decline over 20 years, and b) lung function response to BD among asthmatic subjects compared with nonasthmatic subjects and with regards to current smoking and sex.Methods: Longitudinal analyses of previous lung function decline and FeNO level at follow-up and cross-sectional analyses of BD response and FeNO levels in 4257 participants (651 asthmatics) from the European Community Respiratory Health Survey.Results: Among asthmatic subjects, higher percentage declines of FEV 1 and FEV 1 /FVC were associated with higher FeNO levels (p ¼ 0.001 for both) at follow-up.These correlations were found mainly among non-smoking individuals (p ¼ 0.001) and females (p ¼ 0.001) in stratified analyses. Percentage increase in FEV 1 after BD was positively associated with FeNO levels in non-asthmatic subjects. Further, after stratified for sex and smoking separately, a positive association was seen between FEV 1 and FeNO levels in non-smokers and women, regardless of asthma status.
Conclusions:We found a relationship between elevated FeNO and larger FEV 1 decline over 20 years among subjects with asthma who were non-smokers or women. The association between elevated FeNO levels and larger BD response was found in both non-asthmatic and asthmatic subjects, mainly in women and non-smoking subjects.
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