Madison M Reeves, Sara Aviles Carpintero, Matteo Zanovello, Karen Jansen-West, Mei Yue, Anna Calliari, Yuping Song, Judith Dunmore, Candela Maroto Cidfuentes, Sophie Ball, Jennifer M Kachergus, Heather E Killeen, Bailey Rawlinson, Erica Engelberg-Cook, Michael DeTure, Gregory S Day, Neill R Graff-Radford, Bradley F Boeve, David S Knopman, Ronald C Petersen, Melissa Murray, Aubrey E Thompson, Dennis W Dickson, Pietro Fratta, Leonard Petrucelli, Keith A Josephs, Mercedes Prudencio
These findings point to UNC13A cryptic splicing as a specific driver of cognitive decline in AD, outperforming both genetic risk and other cryptic targets.
BACKGROUND: TAR DNA-binding protein of 43 kDa (TDP-43) is often found in the brains of patients with Alzheimer's disease (AD), where it co-occurs with amyloid β plaques and tau neurofibrillary tangles, and associates with accelerated cognitive decline and brain atrophy. TDP-43's function of repressing the inclusion of cryptic exons (CEs) during RNA splicing is compromised in AD. A single-nucleotide polymorphism (SNP) located within the CE in the UNC13A gene [rs12973192 (C > G)] is associated with higher disease risk and reduced survival in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) by weakening TDP-43 binding promoting CE inclusion.
OBJECTIVE: To investigate the influence of the rs12973192 UNC13A CE SNP and UNC13A cryptic splicing on TDP-43 pathology, survival and cognitive impairment in AD.
METHODS: We evaluated the UNC13A CE SNP in a cohort of 1,672 AD, including 643 AD brains with available cognitive measurements and 73 AD cases for which we measured cryptic RNA levels in the amygdala. We also evaluated a cohort of 466,517 from the UK Biobank to determine associations between the UNC13A CE SNP and dementia diagnosis.
RESULTS: In AD, the UNC13A CE SNP associated significantly with cognitive decline, but not with TDP-43 pathology or with survival. UNC13A cryptic RNA levels in the amygdala were a better predictor of cognitive decline than the UNC13A CE SNP itself, while STMN2-another well-known CE target-exhibited no such association.
CONCLUSIONS: These findings point to UNC13A cryptic splicing as a specific driver of cognitive decline in AD, outperforming both genetic risk and other cryptic targets.