In light of this, several genes linked to other macular, muscular and neurodegenerative diseases have been studied in the context of ALS, including APOE (Alzheimer's Disease, AD), CST3 (age-related Macular Degeneration, MD), OPTN (Open Angle Glaucoma, OAG), GRN (Frontotemporal dementia, FTD), and PSEN1 (AD) [61], [63]–[65], [67], [68], [93]–[104]. Here, APOE is linked to amyotrophic lateral sclerosis.