SNPs in neurotrophin system genes and Alzheimer's disease in an Italian population

Increasing evidence suggests a role for nerve growth factor (NGFB), brain-derived neurotrophic factor (BDNF), and their receptors, nerve growth factor receptor (NGFR), and neurotrophin tyrosine kinase receptors 1 and 2 (NTRK1 and NTRK2), in Alzheimer's disease (AD). However, genetic association between the neurotrophin system genes and AD has been poorly investigated. We genotyped 21 single nucleotide polymorphisms (SNPs) within these genes in a population of Italian AD patients and healthy controls. We found an allele-wise association of rs2072446 on NGFR with familial AD (fAD, p = 0.047), and a genotype-wise association of rs2289656 on NTRK2 with sporadic AD (sAD, p = 0.0036). rs6336 on NTRK1 resulted associated to early-onset sAD in both allele-wise (p = 0.028) and genotype-wise (p = 0.014) analysis, while rs1048218 on BDNF showed allele-wise association with late-onset sAD (p = 0.047). A trend to association with sAD and/or fAD was observed for other SNPs. Our results suggest that genetic variants of neurotrophin system genes might confer susceptibility to AD.