Beyond these studies of common genetic variation, rare genetic variants in RBFOX1 such as copy number variants (CNVs) and loss-of-function mutations have been related to early-onset neurodevelopmental disorders, especially autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) [8–13]; furthermore, case (series) reports have also implicated rare variants in RBFOX1 in developmental delay, intellectual disability, epilepsy, and aggression [14]. This evidence concerns the gene RBFOX1 and Global developmental delay.