SHANK3 deletion or mutation (which we will refer to together as SHANK3 deficiency) is found in about 0.5% of patients ascertained for autism spectrum disorder (ASD), including 0.2% with a SHANK3 mutation identified by sequencing [2-4,7,8] and 0.3% with a SHANK3 deletion, as shown by microarray analyses of over 7,000 individuals with ASD([3,9-15], Autism Genome Project, unpublished). This evidence concerns the gene SHANK3 and hyperinsulinemic hypoglycemia, familial, 4.