The overlapping clinical and neuropathologic features between late-onset apparently sporadic Alzheimer's disease (LOAD), familial Alzheimer's disease (FAD), and other neurodegenerative dementias (frontotemporal dementia, corticobasal degeneration, progressive supranuclear palsy, and Creutzfeldt-Jakob disease) raise the question of whether shared genetic risk factors may explain the similar phenotype among these disparate disorders. To investigate this intriguing hypothesis, we analyzed rare coding variability in 6 Mendelian dementia genes ( APP, PSEN1, PSEN2, GRN, MAPT, and PRNP), in 141 LOAD patients and 179 elderly controls, neuropathologically proven, from the UK. In our cohort, 14 LOAD cases (10%) and 11 controls (6%) carry at least 1 rare variant in the genes studied. We report a novel variant in PSEN1 (p.I168T) and a rare variant in PSEN2 (p.A237V), absent in controls and both likely pathogenic. Our findings support previous studies, suggesting that (1) rare coding variability in PSEN1 and PSEN2 may influence the susceptibility for LOAD and (2) GRN, MAPT, and PRNP are not major contributors to LOAD. Thus, genetic screening is pivotal for the clinical differential diagnosis of these neurodegenerative dementias.
We have used exome sequencing to investigate rare coding variability in Mendelian dementia genes ( APP, PSEN1, PSEN2, GRN, MAPT, and PRNP) in a cohort composed of 141 late-onset sporadic Alzheimer's disease cases and 179 elderly controls, autopsy proven from the UK.
We report a novel mutation in PSEN1 (p.I168T) and a rare variant in PSEN2 (p.A237V), both likely pathogenic.
We conclude that PSEN1 and PSEN2 harbor susceptibility factors for sporadic Alzheimer's disease. By contrast, GRN, MAPT, and PRNP do not play a major role for the development of late-onset sporadic Alzheimer's disease.
Genetic screening is therefore pivotal for a clinical differential diagnosis of sporadic late-onset Alzheimer's disease and other neurodegenerative dementias (frontotemporal dementia, corticobasal degeneration, progressive supranuclear palsy, and Creutzfeldt-Jakob disease).