RET and Hirschsprung disease: Taking advantage of the microarray technique and mouse model, Heanue et al. have demonstrated that both Arhgef3 (Rho guanine nucleotide exchange factor (GEF) 3) and Ctnnal1 (catenin (cadherin associated protein), alpha-like 1) have human homologues that map to previously identified HSCR susceptibility loci, i.e. the RET-dependent susceptibility loci (3p21 and 9q31), which makes them excellent candidate genes for Hirschsprung disease [17–19].