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. The gene discussed is KIFBP; the disease is Goldberg-Shprintzen syndrome.