The Beta 3 Adrenergic Receptor Codon 64 Variant Is Not Associated With Age-at-Diagnosis Of NIDDM Nor With Obesity In The FUSION (Finnish US Investigation Of NIDDM) Study Recent evidence from Pima, Finnish and French samples showed a modest positive association between the Trp64Arg missense variant in the beta 3 adrenergic receptor with earlier age-at-onset for NIDDM together with other indicators of insulin resistance and obesity. We evaluated these hypotheses in 1076 Finnish NIDDM probands and affected sibs in addition to 332 unaffected spouses and non-diabetic controls. There was no evidence for differences in allelic frequencies between diabetic (q= 0.086) and non-diabetic (q=0.098) subjects (P value for difference in proportions=0.42). Furthermore, in diabetics and after stratifying for sex, no differences were seen with age-at-diagnosis for diabetes (self-reported), BMI or weight between those with the variant and those without. The mean age-at-diagnosis for males and females with the variant was 51.45 and 51.49 years respectively, while in those without the variant the corresponding ages were 50.94 and 52.64 years. Possible reasons for not replicating the original results may be due to different methods in assessing age-at-diagnosis, or that the originally reported associations were false positives.