Effect of single-nucleotide polymorphisms on decline of dopamine transporter availability in parkinson’s disease

Abstract

Background and Purpose We aimed to determine the association between the annual changes in dopamine transporter (DAT) availability as measured by 123 I-ioflupane ( 123 I-FP-CIT) single-photon-emission computed tomography and single-nucleotide polymorphisms (SNPs) known to be risk factors in Parkinson’s disease (PD). Methods In total, 150 PD patients were included from the Parkinson’s Progression Markers Initiative database. Specific SNPs that are associated with PD were selected for genotyping. SNPs that were not in Hardy-Weinberg equilibrium or whose minor allele frequency was less than 0.05 were excluded. Twenty-three SNPs met the inclusion criteria for this study. The Krus-kal-Wallis test was used to compare annual percentage changes in DAT availability for three subgroups of SNP. Results None of the 23 SNPs exerted a statistically significant effect (p<0.0022) on the decline of DAT availability in PD patients. However, we observed trends of association (p<0.05) between three SNPs of two genes with the annual percentage change in DAT availability: 1) rs199347 on the putamen (p=0.0138), 2) rs356181 on the caudate nucleus (p=0.0105), and 3) rs3910105 on the caudate nucleus (p=0.0374). A post-hoc analysis revealed that DAT availability was reduced the most for 1) the putamen in the CC genotype of rs199347 (vs. CT, p=0.0199; vs. TT, p= 0.0164), 2) the caudate nucleus in the TT genotype of rs356181 (vs. CC, p=0.0081), and 3) the caudate nucleus in the CC genotype of rs3910105 (vs. TT, p=0.0317). Conclusions Significant trends in the associations between three SNPs and decline of DAT availability in PD patients have been discovered.