The RET proto-oncogene has been described as the major HSCR gene, and over 100 mutations have been identified including large chromosomal deletions which encompass the whole RET sequence, microdeletions and insertions, splicing, and nonsense and missense mutations [2], the last mutations being the most frequent alterations found in HSCR patients. The gene discussed is RET; the disease is Hirschsprung disease.