MNX1 and Currarino triad: Although the former investigations suggested a relationship between the HLXB9 gene and Currarino syndrome—the form of CRS with a triad of sacral agenesis (hemisacrum), presacral mass and anorectal malformation [28,29,30]—a further study by Merello et al. proved that the HLXB9 gene is not involved in the pathogenesis of CRS, but is a causative gene only in Currarino syndrome [31].