TOMM40 (translocase of outer mitochondrial membrane, 40kD) encodes a membrane-bound mitochondrial protein that is adjacent to, and in linkage disequilibrium with, the apolipoprotein E gene. Genotyping is performed by Polymorphic DNA Technologies, Inc. (Alameda, California), blinded to all clinical and pathologic data. The TOMM40'523 genotypes are determined by rs10524523 (chr19:44,899,792-44,899,826, human genome reference assembly GRCh38/hg38), a homopolymer length polymorphism (poly-T), at intron 6 of the TOMM40 gene, as described by Roses et al., 2014. Allele lengths are then categorized based on the number of the poly-T repeats: a short allele ['523-S] is defined by poly-T repeat≤19, a long ['523-L] allele by 20≤poly-T repeat≤ 29;, and a very long allele ['523-VL] by poly-T repeat≥30.

TOMM40'523 genotypes: