Genetic polymorphisms in vitamin E transport genes as determinants for risk of equine neuroaxonal dystrophy

Background Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM) is an inherited neurodegenerative disorder associated with vitamin E deficiency. In humans, polymorphisms in genes involved in vitamin E uptake and distribution determines individual vitamin E requirements. Hypothesis/Objectives Genetic polymorphisms in genes involved in vitamin E metabolism would be associated with an increased risk of eNAD/EDM in Quarter Horses (QHs). Animals Whole‐genome sequencing: eNAD/EDM affected (n = 9, postmortem [PM]‐confirmed) and control (n = 32) QHs. Validation: eNAD/EDM affected (n = 39, 23‐PM confirmed) and control (n = 68, 7‐PM confirmed) QHs. Allele frequency (AF): Publicly available data from 504 horses across 47 breeds. Methods Retrospective, case control study. Whole‐genome sequencing was performed and genetic variants identified within 28 vitamin E candidate genes. These variants were subsequently genotyped in the validation cohort. Results Thirty‐nine confirmed variants in 15 vitamin E candidate genes were significantly associated with eNAD/EDM (P