C9orf72 and amyotrophic lateral sclerosis: Although this experiment was performed only in male hSOD1G93A mice, studies that investigate the efficacy of HEF in various ALS models including female mice, such as mice modeling TAR DNA-binding protein 43 (TDP43) and ORF 72 on chromosome 9 (C9orf72) ALS, are required before it can be established that HEF are therapeutic candidates for patients with ALS.