Association of MAPT haplotype-tagging SNPs with sporadic Parkinson's disease.

Mutations in the tau gene (MAPT) have been found in families with frontotemporal dementia with parkinsonism linked to chromosome 17. In addition, the MAPT H1-clade specific sub-haplotype, H1c, has been strongly associated with the tauopathies, progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) and, to a lesser extent, with Alzheimer's disease (AD). In Parkinson's disease (PD), there have been several reports of association with the MAPT H1-clade. Although weak to inconclusive, this association is supported by meta-analyses of the various studies. To further investigate this baffling role of MAPT in PD, six haplotype-tagging SNPs were genotyped in a large cohort of sporadic PD cases; 324 pathologically confirmed and 248 clinically diagnosed, and 660 controls. In the single-locus association analysis, the H1-clade was associated with an increased risk of PD (p=0.032). In the haplotype-analysis, the sole H2-derived haplotype was under-represented in all of the PD cases compared to controls (p=0.03). There was no significant difference in the distribution of any of the common haplotypes derived from the H1-clade background. Our study supports the hypothesis that genetic variability in the MAPT gene confers susceptibility to PD. However, the effect is not strong, and the H1c haplotype is not involved, suggesting a mechanism that is distinct to that involved in the associated tauopathies and may be explained by the H1/H2 inversion.