ATP7A and X-linked distal spinal muscular atrophy type 3: Our selection is further supported by previous studies showing that abnormal Cu homeostasis increases the production of reactive oxygen species (ROS), resulting in cellular damage, neurodegeneration, and neuroinflammation35–37, and by other studies showing that several ATP7A variants are linked with neurodegenerative diseases such as Menkes disease, occipital horn syndrome, and X-linked distal spinal muscular atrophy type 3, which show similar symptoms as ALS37 (Supplementary Fig. 4).