Abstract
INTRODUCTION: Genetic contributors to early onset Alzheimer's disease (AD) beyond APP and PSEN1/2 remain unknown. Identifying novel loci may reveal disease mechanisms and therapeutic targets. We investigated genetic variants influencing age at onset in early onset families from the Long-Life Family Study (LLFS). METHODS: Six families with at least two early onset cases (onset ≤ 65) were identified among 3476 LLFS participants. Genome-wide linkage analysis of age at onset was followed by single nucleotide polymorphism association. Validation analyses were performed in nine independent cohorts, alongside blood and brain transcriptomic analyses. RESULTS: Three significant linkage regions were identified, including RBFOX1 (logarithm of the odds = 4.41). RBFOX1 variants were associated with age at onset and cognitive phenotypes. A consistent association of RBFOX1 was observed across validation cohorts. Blood transcriptomics revealed RBFOX1 overexpression was associated with an earlier onset. DISCUSSION: RBFOX1 may influence AD age of onset, nominating the gene as a potential therapeutic target for delaying or preventing dementia.