Background: Obstructive sleep apnea (OSA) is a complex disorder characterized by repetitive collapse of upper airway
during sleep which strongly influenced by genetic factors, especially those affect regulation of the sleep-wake cycle and
endothelial function.
Objective: This study investigated the association between single nucleotide polymorphisms (SNPs) in endothelin (EDNRA),
orexin (OX1R, OX2R) and vascular endothelial growth factor (VEGFR1) receptor genes with risk of OSA in Thai population.
Material and Method: All subjects were diagnosed by overnight polysomnography (PSG) before divided into OSA (59) and NOSA (60) groups based on their apnea-hypopnea index (AHI). Serum lipid levels were examined by using enzymatic
colorimetric and homogeneous methods. DNAs were extracted and genotyped the SNPs by polymerase chain reaction (PCR)
and high-resolution melting (HRM) analysis. Genotype distribution were analyzed using Chi-square test of SPSS program version 15.0.
Results: The triglycerides level of OSA patients was significantly higher than NOSA (p-value = 0.002). The SNPs in EDNRA
(rs5335), OX1R (rs2271933), OX2R (rs2292040, rs10456182) and VEGFR1 (rs11149523) genes showed no association with OSA. However, the SNP (rs17675063) in EDNRA gene showed significant differences in genotype distribution in the subjects with and without OSA (p-value = 0.002, odds ratio = 3.29 and 95% CI = 1.86-5.82).
Conclusion: The results suggested that SNP in EDNRA gene (rs17675063) associates with the risk of OSA in Thai population. It may be used as a marker for this disease.

Keywords: Obstructive sleep apnea, Single nucleotide polymorphisms, Endothelin receptor type A, Orexin receptor 1, Orexin receptor 2, Vascular endothelial growth factor receptor type 1