A serotonin malfunction hypothesis by finding clear mutual relationships between several risk factors and symptoms associated with sudden infant death syndrome.

In our recent study allele variants in the promoter of serotonin transporter (5-HTT) gene have been shown as a novel risk factor for sudden infant death syndrome (SIDS). L and XL alleles were more frequent and S allele was less frequent in SIDS victims compared to age-matched controls. Serotonin (5-HT) is suggested as a major agent that is closely involved in the etiology of SIDS. Although many risk factors of SIDS looked mutually unrelated each other, we found in literature many of them other than prone position to change 5-HT levels in the brain. Along with the genetic factors, environmental and temporal factors appear additively to lower the excitatory function of 5-HT to the respiratory center, and finally SIDS might occur. Now the pathophysiological mechanisms and symptoms of SIDS are explained by decreased levels of 5-HT. Copyright 2002, Elsevier Science Ltd. All rights reserved.