Gene expression profile of sporadic and PSEN1 early-onset Alzheimers Disease

Alzheimers disease (AD) is the most common neurodegenerative dementia. Around 10% of cases present an age of onset before 65 years-old, which in turn can be divided in monogenic or familial AD (FAD) and sporadic early-onset AD (EOAD). Mutations in PSEN1, PSEN2 and APP genes have been linked with FAD. The aim of our study was to describe the brain whole-genome RNA expression profile of the posterior cingulate area in EOAD and FAD caused by PSEN1 mutations (FAD-PSEN1). 14 patients (7 EOAD and 7 FAD-PSEN1) and 7 neurologically healthy controls were selected and samples were hybridized in a Human Gene 1.1 microarray from Affymetrix. When comparing controls with EOAD and controls with FAD-PSEN1, we found 3183 and 3351 differentially expressed genes (DEG) respectively (FDR corrected p<0.05). However, any DEG was found in the comparison of the two groups of patients. Microarrays were validated through quantitative-PCR of 17 DEG. In silico analysis of the DEG revealed an alteration in biological pathways related to calcium-signaling, axon guidance and long-term potentiation (LTP), among others, in both groups of patients. These pathways are mainly related with cell signalling cascades, synaptic plasticity and learning and memory processes. In conclusion, the altered biological final pathways in EOAD and FAD-PSEN1 are highly coincident. Also, the findings are in line with those previously reported for late-onset AD (LOAD, onset >65 years-old), which implies that the consequences of the disease at the molecular level are similar in the final stages of the disease.

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Antonell A, Lladó A, Altirriba J, Botta-Orfila T, Balasa M, Fernández M, Ferrer I, Sánchez-Valle R, Molinuevo JL