Lack of association between the BDNF gene Val66Met polymorphism and Alzheimer disease in a Chinese Han population.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by excessive neuronal loss in specific regions of the brain. Among the areas most severely affected are the basal forebrain cholinergic neurons and their projection regions, the hippocampus and the cortex. Several lines of evidence have made brain-derived neurotrophic factor (BDNF) an important candidate gene conferring risk for AD. Recently, several reports investigated the association between a single nucleotide polymorphism (Val66Met, rs6265) of the BDNF gene and AD but yielded ambiguous results. To figure out the association of this single nucleotide polymorphism in the BDNF gene with sporadic AD in a Chinese Han population, we analyzed 513 patients with AD and 575 controls for the genetic association studies. Our results indicated that the distribution of the BDNF genotypes and alleles did not differ significantly. Similar results were observed when the AD and control groups were stratified by age/age at onset and sex. Our data also showed that in the Chinese Han population, the frequencies of the BDNF Met allele (46.5%) and Val allele (53.5%) were significantly different from ethnic groups from Italy, Japan and the USA. The present data revealed no significant effect of the genotypes on the age at onset for developing AD, and no significant association between the genotypes and the severity of the disease. (c) 2007 S. Karger AG, Basel.