Polymorphisms in vitamin D receptor and parathyroid hormone genes in the development and progression of obstructive sleep apnea in Asian Indians

Abstract

ObjectivesVitamin D plays a role in multiple aspects of human physiology, and vitamin D receptor (VDR) and parathyroid hormone (PTH) genes are associated with obesity. No data are available, to our knowledge, on the possible relationship between obstructive sleep apnea (OSA) and genetic variations of VDR and PTH genes. This study aimed to assess the significance of vitamin D and PTH, as well as VDR, and PTH gene polymorphisms with body composition and biochemical investigations in Asian Indians with and without OSA. MethodsIn this study, 120 obese subjects with OSA, 110 obese subjects without OSA, and 70 nonobese subjects without OSA were recruited. Clinical, body composition, anthropometry, and biochemical investigations, as well as a full overnight polysomnography were measured. Genotyping related to VDR (BsmI, ApaI FokI, and TaqI) and PTH (BstBI and DraII) genes were investigated with a quantitative real-time polymerase chain reaction. ResultsThe mean values of the lower serum 25(OH) D (12.9 ± 3.8; P = 0.0001) and higher serum PTH levels (61.9 ± 12.5; P = 0.0001) were observed in obese subjects with OSA. There was an indirect correlation between serum 25(OH) D levels and OSA severity (P < 0.001). VDR (BsmI and FokI) and PTH (BstBI and DraII) genes were significantly associated with OSA (P < 0.05). Analyses of VDR haplotype combination variants (BBFFAATt [odds ratio: 3.45; 95% confidence interval, 0.986–4.567] and BbFFAaTt [odds ratio: 2.86; 95% confidence interval, 1.345–4.981) were more frequent in obese subjects with OSA (P = 0.001). The BBDD and bbDd haplotypes of the PTH gene seems to be a predisposing factor for OSA (P < 0.05). ConclusionsLower serum 25(OH) D levels were significantly observed in patients with OSA and correlate with disease severity. Also, VDR and PTH mutations were found to be highly related with OSA in Asian Indians.