Background: The extended tau H1 haplotype has previously been described in association with progressive supranuclear palsy (PSP). Recently, a new gene called saitohin (STH), nested within an intron of tau, has been discovered. The Q7R polymorphism of STH appears to be related to late onset Alzheimer's disease.
Objectives: To search for genetic changes in the 3'untranslated region (3'UTR) of tau and adjacent sequence LOC147077, and in the coding region of STH in PSP patients.
Methods: The study included 57 PSP patients and 83 healthy controls. The genetic analysis of each region was performed through sequencing. The Q7R polymorphism was studied through restriction enzyme and electrophoresis analysis.
Results: No mutations were found in the regions analysed. The QQ genotype of the STH polymorphism was over-represented in participants with PSP (91.5%) compared with control subjects (47%) (p< or =0.00001). This genotype co-segregated with the H1/H1 haplotype in our PSP cases.
Conclusions: Our results do not support a major role for the tau 3'UTR in PSP genetics. The QQ genotype of STH confers susceptibility for PSP and is in linkage disequilibrium with the H1/H1 haplotype.