However, patients within these studies with long expansions of Rep1 showed increased risk of PD (ORs 3–5×).26 Similar relationships exist for other genetic factors: Apolipoprotein E (APOE) status is linked to adverse outcomes after TBI,27s22 and when combined into polygenic risk scores may predict significant amounts of variability in neurodegenerative outcomes after TBI.s23. The gene discussed is APOE; the disease is Parkinson disease.