UPF2 and Intellectual disability: NMD has also an important role in neuronal development as demonstrated by the fact that mutations, as well as copy number variations in UPF2 and UPF3B, lead to intellectual disability and/or neurodevelopmental disorders in humans, including schizophrenia and autism spectrum disorder (Jolly et al, 2013; Nguyen et al, 2013; Jaffrey & Wilkinson, 2018).