Looking for Genetic Mutations Associated with Neurological Disease

Equine neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM) is the second most common cause of neurologic disease in horses. The condition affects the brainstem and spinal cord and can cause severe gait abnormalities. Studies suggest a genetic basis for the disease, as eNAD/EDM appears to occur in families. Vitamin E deficiency early in life also appears to play a role in disease development. However, despite years of extensive study, researchers have not discovered causative genetic mutations for this condition. The liver performs critical functions in vitamin E storage, metabolism and transport but has not been assessed in horses with eNAD/EDM. In human studies, genes related to liver function have been linked to diseases like eNAD/EDM and may provide novel insight into the cause of eNAD/EDM in horses. In this study, researchers will determine which liver genes and genetic pathways are altered with eNAD/EDM to learn how affected horses process vitamin E. The team will also evaluate Quarter horses' genome with eNAD/EDM. Any promising mutations identified will be assessed in a larger group of horses to pinpoint candidate genes for further study. This study provides the first steps toward identifying causative genes for eNAD/EDM to help inform breeding decisions to reduce or eliminate the incidence of eNAD/EDM in horses. Findings also will inform vitamin E supplementation strategies for foals at high risk for developing this challenging neurological disease.