The β₃-adrenergic receptor TRP64ARG polymorphism and obesity in Alaskan Eskimos

Abstract

OBJECTIVE: A polymorphism in the β₃-adrenergic receptor (β₃-AR) has been described and consists of an amino acid substitution at position 64 where tryptophan is replaced by arginine (Arg allele). This polymorphism appears to be a modest contributor to obesity and non-insulin dependent diabetes mellitus (NIDDM), and may be dependent on gender, gene dosage, ethnic background and environmental factors. We have investigated whether the Trp64Arg polymorphism of the β₃-AR was associated with body mass index (BMI), blood pressure or the presence of NIDDM in Alaskan Eskimos.

SUBJECTS: Two hundred and fifty four Alaskan Eskimos from two distinct villages (Inupiaq and Yupik).

MEASUREMENTS: β₃-AR genotypes were determined by polymerase chain reaction followed by enzymatic digestion.

RESULTS: The frequency of the Arg allele in Alaskan Eskimos was 0.38 and represents the highest Arg allele frequency in any population reported to date. 13.8% of the population were homozygous for the Arg allele, 47.6% heterozygous, and 38.6% lacked the Arg allele. However, the Arg allele was not associated with BMI, blood pressure or the presence of NIDDM in Alaskan Eskimos.

CONCLUSION: These data do not support a significant role for the β₃-AR Arg allele as a marker for obesity (as measured by BMI) or the presence of NIDDM in Alaskan Eskimos. It is possible that other phenotypic variables, not yet available for analysis in this population, may be associated with the presence of the Arg allele.