More rarely, CCHS-compatible phenotypes, including isolated Hirschsprung disease and BRUE and symptoms suggestive of autonomic dysregulation, can be found in association with either chromosomal rearrangements, mainly large deletions, involving the whole PHOX2B locus [43] or contractions of the polyalanine PHOX2B tract [24], thus suggesting the phenotypic spectrum of PHOX2B defects is quite wide and is not yet completely defined. The gene discussed is PHOX2B; the disease is Hirschsprung disease.