Indeed, mutations of the following genes have been identified in either prune belly or the overlapping disease called megacystis microcolon intestinal hypoperistalsis syndrome: ACTA2, encoding α-smooth muscle actin (60); ACTG2, encoding γ2 smooth muscle actin (61); MYH11, encoding a smooth muscle heavy chain protein (62); and MYLK encoding myosin light chain kinase that modifies myosin chains in smooth muscle cells (63). Here, MYLK is linked to megacystis-microcolon-intestinal hypoperistalsis syndrome.