Clinical Features Associated With the Homozygous Trp⁶⁴Arg Mutation of the ß3-Adrenergic Receptor

No Evidence for Its Association With Obesity in Japanese

From the Third Department of Internal Medicine, Faculty of Medicine, University of Tokyo; and the Second Department of Internal Medicine, Faculty of Medicine, Nippon Medical School (Y.F.), Japan.

Abstract—To characterize the clinical features associated with the Trp⁶⁴Arg mutation of the ß3-adrenergic receptor (ß3-AR), the effects of this mutation, in particular the homozygous state (Arg/Arg), on obesity, blood pressure, and plasma lipoproteins were investigated in 2 populations: subjects residing on a small isolated island (group 1; n=746) and patients residing in Tokyo who attend a clinic for metabolic diseases (group 2; n=371). The allelic frequency of the Trp⁶⁴Arg mutation was 23.4% in group 1 and 18.3% in group 2. No significant difference in the body mass index was observed between subjects with 3 different genotypes in each group. There was a trend that the Arg/Arg had higher systolic blood pressure than the Trp/Trp in both groups, but the differences were not statistically significant. The plasma LDL cholesterol levels were significantly lower in Arg/Arg than in Trp/Trp in men from the group 1 cohort (2.82±0.84 versus 3.19±0.7 mmol/L, P<0.05). These results suggest that the homozygous Trp⁶⁴Arg mutation is not a major contributing factor for obesity, but potentially contributed to higher systolic blood pressure and low plasma levels of LDL cholesterol in Japanese men.

Key Words: ß3-adrenergic receptor • obesity • hypertension • diabetes • cholesterol