Nerve growth factor and its receptor with tyrosine kinase activity (TrkA) have been implicated in the development of Alzheimer's disease (AD). Entire coding regions of TrkA gene harboring exons 1 through 17 were sequenced in 114 patients with sporadic AD and 112 control subjects in a Japanese population, and six known and two novel single nucleotide polymorphisms were identified, but no mutation associated with sporadic AD was identified. Concurrently, case-control analysis of TrkA gene A1674G polymorphism in 534 patients with sporadic AD and 454 control subjects has revealed no significant differences in TrkA genotype or allele frequencies even after stratification for Apolipoprotein E epsilon4 carrier statuses. Thus, the TrkA genotype does not appear to influence the risk of developing sporadic AD in a Japanese population.