Alzheimer's disease and 5-HTTLPR polymorphism of the serotonin transporter gene: no evidence for an association.

Recently two independent research groups consistently reported a significant association between the serotonin transporter (5-HTT) gene and late-onset sporadic Alzheimer's disease (AD). They found that the "short" allele of the 5-HTT gene-linked polymorphic region (5-HTTLPR), which is associated with reduced transcriptional activity of the gene, increases the risk of developing late-onset AD. The present study tried to replicate this finding in a Japanese sample. We genotyped 41 patients with early-onset AD (<65 years), 82 with late-onset AD, and 336 controls. There was no significant difference in genotype or allele distribution between either patient group and controls in our sample, suggesting that the 5-HTTLPR does not play a major role in the pathogenesis of AD in Japanese.