Objective: Evaluate the association of MAPT haplotype with the risk of PSP-CBS and CBD severity of tau pathology by studying the survival rate of both groups.

Background: Progressive supranuclear palsy(PSP) and Corticobasal degeneration(CBD) are tauopathies whose differential diagnosis remains problematic. The distinction became more challenging when it comes to the corticobasal syndrome phenotype of PSP(PSP-SCB). Common and rare variants in the microtubule-associated protein tau (MAPT) gene increase the risk of both diseases.

Method: We conducted a retrospective, descriptive study in the Neurology Department of Razi University Hospital, including PSP-CBS patients according to the 2017MDS criteria and for CBD according to the Armstrong criteria(2013). Survival was explored using Kaplan-Meier analysis. Demographic, clinical, neuropsychological features and MAPT haplotype H1 and H2 profiles were analyzed in the survival analysis.

Results: We collected 25 cases of CBD and 10 cases with PSP-CBS. There was no significant difference between both groups in terms of carriage of H1 and H2 MAPT haplotype (p=0.8). There was statistically significant differences in median survival between H1 and H2 haplotype carriers(respectively 5 years vs 7years, p=0.014) regardless of phenotypes (PSP-CBD and CBD). While comparing the survival of cases carriage of MAPT haplotype (H1 and H2) with taking into account the clinical diagnosis (PSP-CBD or CBD), we found a significant association, p=0.012. In fact, CBD cases with H1 had median survival rate of 8. While the PSP-CBS cases carriers of H1 had the less survival rate (4 years). For cases carriers of H2-MAPT, the PSP-CBS and CBD cases had longer survival (6 and 10 years respectively). No significant association were noted according to gender and MAPT haplotypes.

Conclusion: PSP-SCB cases had lower survival, probably due to more severe tau pathology by carrying the H1 haplotype associated to more tau protein misfolding. However, cases with CBD had longer survival than PSP-CBS.  Our finding expand the current understanding of the role of MAPT haplotype in susceptibility and neuropathologic severity of PSP-CBS patients.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/differential-effect-of-mapt-haplotype-on-survival-in-cbd-and-psp-scb-phenotype/