Genome-wide association studies of TDP-43 proteinopathy and hippocampal sclerosis reveal shared genetic associations with APOE and TMEM106B.

INTRODUCTION: Transactive response DNA binding protein 43 kDa (TDP-43) proteinopathy has been linked to cognitive decline and often co-occurs with hippocampal sclerosis (HS). To identify genetic markers of TDP-43 proteinopathy and HS, we performed genome-wide association studies (GWASs) of HS and TDP-43 inclusions. METHODS: Genetic data were obtained through the Alzheimer Disease Genetics Consortium and collaborating sites (HS: N = 9509; TDP-43: N = 4669). Statistical analyses included association analysis with HS and TDP-43 inclusions and meta-analysis, a mediation analysis, and fine mapping of the transmembrane protein 106B (TMEM106B) region. RESULTS: Two regions achieved genome-wide significance with TDP-43: apolipoprotein E (APOE) and TMEM106B. Three loci reached genome-wide significance with HS: APOE, TMEM106B, and granulin precursor (GRN). Fine mapping of TMEM106B identified 93 variants in the credible set. Mediation analyses showed that genetic effects on HS were partially mediated through TDP-43 proteinopathy. DISCUSSION: We identified associations with TDP-43 inclusion and HS, showing shared genetic risk across frontotemporal lobar degeneration, amyotrophic lateral sclerosis, Alzheimer's disease, and limbic-predominant age-related TDP-43 encephalopathy. HIGHLIGHTS: HS and TDP-43 contribute to dementia and often co-occur. The etiology and relationship of HS and TDP-43 remains unclear. HS and TDP-43 share genetic risk factors in the genes APOE and TMEM106B. Genes have direct effects on HS, with additional effects mediated through TDP-43.