A novel association was observed between AR repeat length and ALS survival, which may relate to androgen biology, as androgen ablation can extend survival and disease duration in SOD1 ALS mouse models.86 Since changes in CAG repeat lengths in AR have been associated with changes in androgen levels, this could imply a possible role in ALS survival.87 However, this was not replicated in a smaller Norwegian cohort, indicating further research is needed. This evidence concerns the gene AR and amyotrophic lateral sclerosis.