The Significance of thebeta3 Adrenergic Receptor Gene Polymorphism in Obese Koreans

Kim, Byoung Joon; Kim, Sung Hoon; Kim, Dong Jun; Hahm, Jong Ryeal; Kim, Jin Seok; Ahn, Kyu Jeung; Chung, Jae Hoon; Min, Yong Ki; Lee, Myung Shik; Lee, Moon Kyu; Kim, Kwang Won

Abstract

BACKGROUND: The b3 adrenergic receptor (b3-AR), expressed mainly in visceral fat of human, is involved in regulation of lipolysis and thermogenesis. The missense mutation of b3-AR gene, resulting in the replacement of tryptophan by arginine at position 64 (Trp64Arg), is associated with decreased resting metabolic rate, weight gain and development of obesity. The purpose of this study was to investigate the frequency of the b3-AR gene polymorphism in obese Koreans. Subjects and
METHODS
b3-AR genotype was determined in 87 healthy Koreans who visited SMC for the purpose of health checking from Dec/1996 to Feb/1997. Oral glucose tolerance test was performed with 75 g glucose. Lipid profiles, insulin, C-peptide were measured. Anthropometric data was obtained from physical examination and medical records. The subjects with previously diagnosed diabetes mellitus, other endocrine diseases or chronic illness were excluded. To determine the polymorphism, genomic DNA was isolated and PCR and RFLP by MvaI were carried.
RESULTS
1. The difference in frequency of Trp64Arg mutation between two groups was highly significant. (12 subjects (63%) in obese group and 21 subjects (30%) in non obese group, p<0.02) 2. There was significantly high allele frequency in obese group. (obese group: 32 %; non obese group: 15 %, p<0.02). 3. According to BMI, there were significantly high WHR (0.88+0.04 vs 0.83+0.06,p=0.01), total body fat (29.8+7.4 vs 24.4+6.5%, p=0.01) and systolic blood pressure(132+19 vs 124+14mmHg, p=0.04) in obese group. 4. According to b3-AR genotype, there were significantly high WHR (0.830.056 vs. 0.860.05) and 120 min (260.5+171. 5 vs 355.9+234.6 pmol/L, p=0.04) insulin level during OGTT in heterozygote group.
CONCLUSION
These results suggest that the frequency of the b3-AR gene mutation was significantly higher in obese Koreans and b3-AR gene polymorphism might play a role in the pathogenesis of obesity.