Serotonin transporter promoter genotype and illness recurrence in mood disorders.

We tested the hypothesis that allelic variation of 5-HTT linked polymorphic region (5-HTTLPR) could influence illness onset and recurrence in 129 bipolar and 128 unipolar recurrent patients. Among bipolar patients, homozygotes for the short variant showed an earlier age at onset and a lower recurrence rate than heterozygotes and homozygotes for the long variant. Unipolar patients showed a trend toward the same difference. Data support a role for 5-HTTLPR in course of affective illness.