FUS and amyotrophic lateral sclerosis: However, the use of knock-in models that have a slower rate of progression, with physiological expression of the mutation, is more informative for both early-stage disease processes and for following the effects of ageing; such models include genetically humanised FUS-ALS (Devoy et al. 2017) and HD (Heng et al. 2007) knock-in mice that exhibit age-dependent, progressive neurodegeneration.