Association analysis of brain-derived neurotrophic factor Val66Met polymorphisms with Alzheimer's disease and age of onset.

Because of a decrease in central brain-derived neurotrophic factor (BDNF) levels in Alzheimer's disease (AD) and the important role of BDNF in neuronal survival, BDNF may represent a candidate gene conferring susceptibility to AD. Recently, a functional BDNF Val66Met polymorphism has been associated with AD in an Italian population. In the present study, we investigated a possible role of this BDNF polymorphism in the susceptibility of AD or AD onset in a Chinese population. Comparing AD patients and controls, the distribution of the BDNF genotypes and alleles did not differ significantly. The onset age was not significantly different comparing the three BDNF genotype groups. Our negative findings suggest that it is unlikely that the BDNF Val66Met polymorphism plays a major role in the pathogenesis of AD in the Chinese population and do not support previous findings that homozygosity for the 66Val allele confers an increased risk for AD. Further studies with genetic variations in BDNF relating either to AD-associated depression or to the AD treatment response are suggested. Copyright 2004 S. Karger AG, Basel