Association of genetic polymorphisms of glutamate decarboxylase 2 and the dopamine D2 receptor with obesity in Taiwanese subjects

BACKGROUND AND OBJECTIVES: It has been proposed that glutamate decarboxylase 2 and the dopamine D2 receptor are involved in the brain reward cascade to increase carbohydrate craving and cause eating disorders. We investigated the association between the polymorphisms of the GAD2 and DRD2 genes and obesity with a higher body mass index (BMI) in Taiwanese patients. DESIGN AND SETTING: A retrospective, case-control study at Antai Tian-Sheng Memorial Hospital from 1 January to 31 December 2009. SUBJECTS AND METHODS: Of 300 subjects enrolled in the study, 132 were obese (BMI≥30 kg/m(2)) and 168 controls were not obese (BMI≤24 kg/m(2)). The polymorphisms of GAD2 (+61450 C/A), (+83987 T/A) and DRD2 (S311C) were characterized, respectively, by polymerase chain reaction-restriction fragment length polymorphism. The genotype and allele frequencies of the polymorphisms in this study were statistically analyzed. RESULTS: The genotype and allele frequencies of the GAD2 (+83987 T/A) and DRD2 (S311C) were significantly different between cases and controls (P=.001 for both). The frequencies of TT genotype and T allele of the GAD2 (+83987 T/A) as well as the frequencies of Ser/Cys genotype and Cys allele of DRD2 (S311C) were higher in cases compared to controls (P=.034 and .036 for both). CONCLUSIONS: The study demonstrated a statistically significant difference in the frequency of the GAD2 (+83987 T/A) and DRD2 (S311C) genes between cases and controls in Taiwanese subjects.