KMT2A and Global developmental delay: To dissect the neurodevelopmental spectrum of de novo KMT2A variants, we examined the reported phenotypes of the 127 individuals with de novo LoF or missense variants in KMT2A. The top five reported phenotypes were ID (59.1%), developmental delay (48.8%), hypotonia (30.7%), delayed speech and language development (22.0%), and malformations in central nervous system (16.5%) (Fig. 4).