Direct genetic evidence for involvement of tau in progressive supranuclear palsy

Objective: To confirm whether a dinucleotide repeat sequence in an intron of the microtubule-associated protein tau is associated with progressive supranuclear palsy (PSP) in an independent study population and to establish an improved methodology for allelotyping. Background: It has recently been reported that a genetic variant of tau, known as the AO allele, was represented excessively in PSP patients when compared with control subjects. Methods: In a multicenter study, the authors examined the allelic distribution of this dinucleotide repeat marker in a set of clinically ascertained PSP patients (n = 30), multiple system atrophy (MSA) patients (n = 35), and matched control subjects (n = 70). Individuals were allelotyped using automated analysis of fluorescently labeled PCR products. Results: The AO allele was significantly overrepresented in the PSP patients (93.3% versus 76.4%; p = 0.0067; odds ratio [OR] = 4.33; 95% confidence interval [CI], 1.36 to 13.60), but not in the MSA patients. Likewise, AO homozygotes were overrepresented in the PSP group (86.7% versus 61.1%; p = 0.02; OR = 4.14; 95% CI, 1.19 to 14.48) compared with control subjects. Conclusions: The findings of this study, which is the largest to date, support those of a previous investigation that used pathologically confirmed PSP patients. These data provide additional strong evidence that genetic variation at or near the tau gene plays an important role in the pathogenesis of PSP.