To further explore genetic heterogeneity in HSCR, we have performed CGH, using a custom array with high density probes and focusing on a total of 20 candidate regions/genes already known to be involved in HSCR, on a selected panel of 55 sporadic HSCR previously genotyped at the RET locus [6] and four HSCR patients with already known chromosomal aberrations. This evidence concerns the gene RET and Hirschsprung disease.