KIF1A and Global developmental delay: Individuals with the KIF1A p.R316W variant identified in P781 have also previously been reported.26,28 A homozygous pathogenic stop-gain mutation in NT5C2, NM_001134373.2: c.115C>T: p.R39*, was identified in a female, P718, who had spastic diplegia, developmental delay, autism, attention deficit hyperactivity disorder (ADHD), visual problems and severe behavioural problems and was from a consanguineous family.