Gln27Glu variant of the β2-adrenergic receptor gene is not associated with obesity and diabetes in Japanese-Americans

Abstract

The β3-adrenergic receptor (AR) gene variant (Trp64Arg) has been reported to be associated with obesity and insulin resistance in humans. However, this association remains controversial. We investigated the relationships between the β2-AR gene variant (Gln27Glu) and obesity, insulin resistance, and serum lipids in Japanese-Americans. The frequency of an abnormal Gln27Glu allele in the β2-AR gene in 652 subjects was 0.092 in males, 0.077 in females, and 0.084 overall, markedly lower than the previously reported value of 0.4 in Caucasian men and women. In both males and females, there were no differences in the indices of obesity, insulin resistance, and serum lipid levels between the subjects with and without the β2-AR gene (Gln27Glu) variant in patients with normal glucose tolerance (NGT), impaired glucose tolerance (IGT), or diabetes (DM). The frequency of the β2-AR gene (Gln27Glu) variant tended to increase with worsening of glucose tolerance, but the differences were not statistically significant. Furthermore, there were no differences in the frequency of the β2-AR gene variant in either males or females with obesity (body mass index [BMI], ≥25.2). Even in Japanese-Americans, who have a more westernized life style than Japanese, the association of the β2-AR gene (Gln27Glu) variant with the parameters of obesity, insulin resistance, and serum lipid level has yet to be clarified. We conclude that the β2-AR gene (Gln27Glu) variant might not be an important factor for obesity or IGT in Japanese subjects.