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

► Serotonin system gene variants (SLC6A4, HTR2A) were investigated in Alzheimer's disease (AD). ► No association was found between 5-HTTLPR, STin2-VNTR or HTR2A T102C polymorphisms and AD. ► The results suggest a potential epistatic effect of 5-HTTLPR and HTR2A polymorphisms on AD risk. ► 5-HTTLPR L/L and HTR2A C/C carriers showed a 2-fold increased susceptibility to AD.