Methods
About 4514 unrelated Caribbean Hispanics (2451 cases and 2063 controls) were selected for genome-wide association analysis. Significant loci were further tested in the expanded cohort that also included related family members (n = 5300). Two AD-like transgenic mice models (J20 and rTg4510) were used to study gene expression. Independent data sets of non-Hispanic Whites and African Americans were used to further validate findings, along with publicly available brain expression data sets.
Objective
In the context of late-onset Alzheimer's disease (LOAD) over 20 genes have been identified but, aside APOE, all show small effect sizes, leaving a large part of the genetic component unexplained. Admixed populations, such as Caribbean Hispanics, can provide a valuable contribution because of their unique genetic profile and higher incidence of the disease. We aimed to identify novel loci associated with LOAD.
Results
A novel locus, rs75002042 in FBXL7 (5p15.1), was found genome-wide significant in the case-control cohort (odd ratio [OR] = 0.61, P = 6.19E-09) and confirmed in the related members cohorts (OR = 0.63, P = 4.7E-08). Fbxl7 protein was overexpressed in both AD-like transgenic mice compared to wild-type littermates. Publicly available microarray studies also showed significant overexpression of Fbxl7 in LOAD brains compared to nondemented controls. single-nucleotide polymorphism (SNP) rs75002042 was in complete linkage disequilibrium with other variants in two independent non-Hispanic White and African American data sets (0.0005 < P < 0.02) used for replication. Interpretation: FBXL7, encodes a subcellular protein involved in phosphorylation-dependent ubiquitination processes and displays proapoptotic activity. F-box proteins also modulate inflammation and innate immunity, which may be important in LOAD pathogenesis. Further investigations are needed to validate and understand its role in this and other populations.