C9orf72 and amyotrophic lateral sclerosis: Similarly, Polgár and colleagues observed that serum transfers from ALS patients with the C9orf72 mutation into ventral spinal cord mice causes increased calcium levels in MNs, thus resulting in neurodegeneration [51]; similar data were provided by Obál and colleagues through the long-term intraperitoneal injection of sera from ALS patients [52].