Serotonin transporter and saitohin genes in risk of Alzheimer's disease and frontotemporal lobar dementia: preliminary findings.

Serotonergic transmission impairment and abnormal phosphorylation of tau protein have been implicated in the physiopathology of Alzheimer's disease (AD) and frontotemporal lobar dementia (FTLD). Associations between a functional polymorphism (5-HTTLPR), in the promoter region of the serotonin transporter gene, and susceptibility to sporadic AD and FTLD have been reported. A polymorphism (Q7R) in saitohin gene inside the microtubule-associated protein tau gene has also been related to dementia. To determine the possible role of the two polymorphisms in susceptibility to AD and FTLD, we performed a case-control study collecting 218 Italian sporadic dementia patients and 54 controls. We found a significant excess of 5-HTTLPR short alleles and an interaction between 5-HTTLPR and Q7R polymorphisms in demented subjects. Our study confirms the role of 5-HTTLPR as a potential susceptibility factor for sporadic dementia in the Italian population, and suggests a possible interaction between 5-HTTLPR and Q7R polymorphisms in neurodegenerative diseases.