Association between the leptin receptor gene polymorphism and lipoprotein profile in Chinese type 2 diabetes

Objective: Leptin has been shown to have a major influence on plasma lipid and lipoprotein metabolism through leptin receptors (LEPR). Genetic studies have been implicated common variants in the human LEPR gene were associated with hyper-insulinemia, type 2 diabetes and leptin levels. In this study, we examined the distribution of the LEPR gene G3057A polymorphism and the association between plasma leptin levels and lipoprotein profile in Chinese type 2 diabetes. Methods: 186 unrelated patients with type 2 diabetes and 150 normal glucose tolerances (NGT) controls were recruited. Hemi-nested PCR-RFLP and PCR direct sequence analysis were used to analysis the LEPR G3057A genotype. Plasma leptin levels were measured using radioimmunoassay kit. Plasma lipid levels triglycerides (TG), total cholesterol (CH), high density lipoprotein lipoprotein cholesterol (HDL-C), low density lipoprotein lipoprotein cholesterol (LDL-C), apolipoprotein Al and apolipoprotein B were measured routinely after overnight fasting. Results: The frequency of the mutant A allele was 57% in diabetic patients versus 56% in normal glucose tolerances controls. The distribution of the three genotypes in control group was as follows: GG genotype, 36.0%; GA genotype, 15.3%; and AA genotype, 48.7%. This genotype distribution did not differ between control subjects and type 2 diabetic patients in which 33.3% were GG, 18.3% were GA and 48.4% were AA (chi(2) = 1.17, P > 0.05). Plasma leptin levels were significantly higher in the diabetic patients (35.72 +/- 2.85) than those in NGT subjects (8.67 +/- 0.35), but there was no statistical difference between LEPR genotypes and plasma leptin levels in the diabetic patients or in NGT control subjects. However in type 2 diabetic groups, AA genotype at nucleotide 3057 had higher levels of TG and LDL-C, and lower levels of HDL-C (P < 0. 01). Conclusion: The LEPRG3057A mutation was common in the Chinese population, this polymorphism was not associated with the glucose metabolic parameters and plasma leptin levels in Chinese subjects, but positively associated with plasma TG and LDL-C levels, negatively associated with plasma HDL-C levels in Chinese diabetic patients. It may contribute to the onset of type 2 diabetes by regulating lipid metabolism and affecting the distribution of local body mass. (C) 2007 Diabetes India. Published by Elsevier Ltd. All rights reserved.