No association between a polymorphic CAG repeat in the human potassium channel gene hKCa3 and bipolar disorder

A recent case‐control study suggested that modest enlargements of a CAG repeat in the hKCa3 potassium channel may be associated with bipolar disorder. We tried to replicate this result in a UK Caucasian sample of 203 DSM‐IV bipolar I disorder patients and 206 controls group‐matched for age and sex. Using the same model of analysis as the earlier study, bipolar probands did not have a higher frequency of alleles with greater than 19 repeats than controls (χ2 = 1.44, 1 df, P = 0.23). Similarly, comparison of the distributions of repeat sizes between probands and controls did not approach statistical significance (Mann‐Whitney U test, P = 0.35). We conclude that our data provide no support for the hypothesis that variation at the hKCa3 gene contributes to susceptibility to bipolar disorder. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 88:57–60, 1999. © 1999 Wiley‐Liss, Inc.