OBJECTIVE: Catechol O-methyltransferase (COMT) is an enzyme that
inactivates catecholamines. Two common COMT alleles determine high and low
activity of the enzyme. Previous studies using biochemical methods found
lower enzyme activity in patients with major depression and bipolar
disorder in comparison with control values, suggesting that a dysfunction
in catecholamine metabolism may be related to the etiology of depression.
METHOD: The authors studied two recently described DNA polymorphisms at the
COMT gene (a silent C256G mutation and a structural mutation, Val-108-Met)
in 88 patients with bipolar disorder and in 113 healthy comparison
subjects, all of Spanish origin. RESULTS: The frequency of the C256 allele
was 0.58 in the patients and 0.54 in the comparison subjects. The frequency
of the Val108 variant was 0.57 for both the patients and the comparison
subjects. No allelic or genotypic associations were observed. CONCLUSIONS:
The lack of association suggests that the COMT gene is not a major risk
factor for bipolar disorder.