KAT6A and Hirschsprung disease: Namely, two different clinical entities characterized by genetic heterogeneity with high phenotypic overlapping such as Goldberg Shprintzen Megacolon Syndrome—GSMCS (KIF1BP)—associated with Hirschsprung disease, while ARTHS (KAT6A), as opposed to megacolon, is characterized by gastrointestinal obstruction/malrotation.