Variation at the serotonin transporter gene influences susceptibility to bipolar affective puerperal psychosis

Up to half of parous females with bipolar disorder (manic depression) develop an episode of severe psychiatric disturbance, usually called puerperal psychosis, within a few days of giving birth. We report significant evidence (p<0·003) that variation at the serotonin transporter gene exerts a substantial (odds ratio=4) and important (population attributable fraction=69%) influence on susceptibility to such episodes.