We genotyped rs4680 in a sample of 163 patients affected by bipolar disorder type I, and assessed the personal history of recurrence of the illness.
We observed a significant association between homozygosis for the rs4680 COMT low-activity variant and a reduced recurrence of manic, but not depressive, episodes during the course of the illness.
We suggest that rs4680 could be an inheritable aspect of the mechanisms of dopamine regulation that influence the individual susceptibility of patients with bipolar disorder to develop manic episodes of illness.