For example, motoneurons are used to study spinal muscular atrophy (SMA) and cardiomyocytes[2] are used to study arrythmia. This can allow for a better understanding of the pathogenesis and the development of new treatments through drug discovery.[6] Immature PSC-derived cell types can be matured in vitro by various strategies, such as in vitro ageing, to modelize age-related disease in vitro. Major diseases being modelized with PSCs-derived cells are amyotrophic lateral sclerosis (ALS), Alzheimer's (AD), Parkinson's (PD), fragile X syndrome (FXS), Huntington disease (HD), Down syndrome, Spinal muscular atrophy (SMA), muscular dystrophies,[13][14] cystic fibrosis, Long QT syndrome, and Type I diabetes.[6]