Notably, we identified double mutations in a 52-year-old female (PSEN2 p.M239I and MAPT p.R5H), but her daily living ability remained intact, and the double mutation did not accelerate the cognitive decline, further expanding the phenotype spectrum of the mutation and supporting the phenotypic heterogeneity among subjects carrying the same MAPT mutations. The gene discussed is MAPT; the disease is Mental deterioration.