In fact, associations between AD risk and the T allele of the rs56164415 (C270T) [3] or the Met allele of the rs6865 [53] of the BDNF gene were found in females, and female-specific association of BDNFVal66Met and BDNF expression in brain tissues were described [45], indicating BDNF as a female-specific risk gene for AD. This evidence concerns the gene BDNF and Alzheimer disease.