Association of the 223A/G LEPR Polymorphism with Serum Leptin Levels in Iranian Subjects with Type 2 Diabetes

Leptin, an adipocyte-derived hormone, has a pivotal role in the regulation of body weight through acting on its specific leptin receptor (LEPR). The 223A/G polymorphism of the LEPR gene is one of the most common polymorphism in all populations. In this study, we aimed to investigate the impact of the 223A/G polymorphism of the LEPR gene on serum levels of leptin in type 2 diabetes mellitus (T2DM) in a sample of Iranian population. One hundred and forty-four T2DM patients were screened and compared to 147 healthy controls. The 223A/G LEPR polymorphism was genotyped using polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP). The serum levels of leptin were measured. The mean serum levels of leptin in T2DM patients were significantly higher than that of healthy control subjects; 22.90 ng/ml (95 % confidence interval [CI] = 20.79 – 25.23) vs. 8.70 ng/ml (95% CI = 7.87 – 9.63). The genotypes (AA, AG, and GG) distributions of the 223A/G polymorphism were 55.5 %, 41 %, and 3.5 % in T2DM and 54.4 %, 42.2 %, and 3.4% in healthy controls. The results showed no significant differences in the 223A/G LEPR genotype and allele frequencies between T2DM and control subjects (χ2 = 0.043, P = 0.979 and χ2 = 0.003, P = 0.957), respectively. In addition, the serum leptin levels were markedly higher in subjects with GG genotype than those with AG or GG genotype only in T2DM The 223A/G LEPR gene polymorphism is associated with markedly increased serum leptin levels in T2DM. However, no differences were determined in genotype and allele frequencies between T2DM patients and control subjects.