The Relationship between Obstructive Sleep Apnea and Gln223Arg Polymorphism in Human Leptin Receptor Gene

Abstract

Leptin is derived from an adipocyte and acts through the leptin receptor (LEPR). Gln223Arg polymorphism of the LEPR gene is thought to be associated with impaired signaling capacity of LEPR and with higher mean circulating levels of leptin and obesity; therefore, it may contribute to the pathogenesis of obstructive sleep apnea syndrome (OSAS). The aim of this study was to investigate the frequency of distribution of LEPR gene polymorphism (Gln223Arg) in OSAS patients in relation to polysomnographic traits and phenotype. In total, 230 men (152 OSAS patients and 78 controls) were included in the study. All participants were evaluated by polysomnography in addition to anthropometric, metabolic, and hemodynamic variables. The relationship between these phenotypes and polymorphism of the LEPR gene was investigated by PCR-RFLP. There was no difference between the genotype frequencies of the Gln223Arg polymorphism in the OSAS and control groups. However, OSAS patients carrying the R allele (RR and QR genotypes) had significantly lower Body Mass Index (BMI) than those carrying the Q allele (QQ). OSAS patients with the RR genotype had a significantly lower diastolic blood pressure value than those with the QQ and QR genotypes. When all participants were grouped by blood pressure, the genotype frequency of RR individuals was more prevalent among normotensive men compared to hypertensive men. Gln223Arg polymorphism of LEPR does not seem to be associated with OSAS. This polymorphism may, however, predispose the carrier to reduced BMI and blood pressure. Further studies are needed to unveil the genetic basis of OSAS pathophysiology.