Sex has been reported to be a risk factor in driving phenotype with one study showing females have a higher prevalence for C9orf72 HRE in ALS in a meta-analysis study (Trojsi et al., 2019) whilst males presented with a shorter survival time based on Cox proportional hazard regression multivariate analysis (Curtis et al., 2017). This evidence concerns the gene C9orf72 and amyotrophic lateral sclerosis.