Leptin and leptin receptor gene polymorphisms in obstructive sleep apnea: a HuGE review and meta-analysis

Several epidemiological studies have been conducted to examine the association between leptin and leptin receptor (LEPR) gene polymorphisms and risk of obstructive sleep apnea (OSA). However, the results remain conflicting rather than conclusive. The aim of this study was to investigate associations of leptin and LEPR polymorphisms and risk of OSA. We carried out a search in MEDLINE, EMBASE, and Chinese National Knowledge Infrastructure (CNKI) databases for relevant studies. Data were extracted using a standardized form and pooled odds ratios (ORs) with 95 % confidence intervals (CIs) were calculated to assess the strength of the association. Overall, no statistically significant association of OSA risk and polymorphisms of Gln233Arg, Lys109Arg, Lys656Asn, 19A/G, Pro1019Arg, and 2548G/A was found. However, in the stratified analysis by ethnicity, Gln233Arg polymorphism was associated with a significantly decreased risk of OSA in European (homozygote comparison: OR = 0.35, 95 % CI = 0.14-0.85, P = 0.02), but not for Asian population. Our study suggested that leptin and LEPR polymorphisms had no association with OSA risk in all examined patients, whereas there was an association between Gln233Arg polymorphism and OSA risk in Europeans.