Serotonin transporter and serotonin receptor 2A gene polymorphisms in Alzheimer's disease.

Genetic variants of the serotonergic neurotransmitter system are potential contributing factors in the pathological processes underlying Alzheimer's disease (AD). We examined polymorphisms of the serotonin transporter (SLC6A4) and serotonin receptor 2A (HTR2A) genes for possible association with AD, and therefore genotyped 5-HTTLPR, STin2-VNTR and HTR2A T102C polymorphisms in 252 Hungarian AD patients and 234 ethnically matched control individuals. We did not detect statistically significant differences in genotype distribution comparing the AD and the control group when the polymorphisms were investigated separately. Logistic regression analyses, however, revealed an interaction effect between 5-HTTLPR and HTR2A T102C (p=0.019), but not between 5-HTTLPR and STin2-VNTR (p=0.494) or STin2-VNTR and HTR2A T102C (p=0.310) polymorphisms. Our study suggests no individual influence of the investigated polymorphisms but a potential combined effect of the 5-HTTLPR L/L and HTR2A T102C C/C genotypes on AD risk. However, the results need to be treated with considerable caution, and further analyses in larger samples are required.