Objective: To investigate the association between the polymorphisms of melanocortin-4 receptor (MC4R) gene and obesity.
Methods: The genotypes of three polymorphisms, nt-216C/T, nt-178A/C, and Val103Ile, were determined through DNA sequencing in 563 Chinese from Shanghai, including 258 individuals with body mass index (BMI) over 30 kg/m(2) and 305 individuals with BMI less than 23 kg/m(2). Height and body weight were measured to calculate BMI. Blood pressure was measured. Waistline, hipline, and femoral waist to calculate the waist-to-hip ratio and waist-to-femoral ratio were measured. Oral glucose tolerance test was conducted to detect the plasma glucose level during fasting condition and 120 minute after glucose loading. The levels of serum lipids, including total cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol.
Results: (1) The frequencies of nt-216C/T, nt-178A/C, and Val103Ile were all less than 5%. (2) Logistic regression showed that the Val103Ile variant was an independent risk factor for obesity (OR = 0.414, P = 0.040). The frequency of Ile was less in the obese individuals compared with the controls. (3) In the controls and obese individuals, no association was detected between the genotypes and phenotypes.
Conclusion: Val103Ile variant of MC4R gene is associated with obesity in Chinese.