Since the presence of Hirschsprung disease is related to NPARMs and the number of alanine repeats, we suggest performing CCHS genetic investigation and periodical assessment also in patients without a clear history of CCHS but affected by Hirschsprung disease.
Most NPARMs are located in exon 3 of PHOX2B and result in a more severe clinical presentation including Hirschsprung disease (HSCR) and/or peripheral neuroblastic tumors (PNTs).
Germline non-polyalanine repeat expansion mutations in PHOX2B (PHOX2B NPARM) predispose to peripheral neuroblastic tumors (PNT), frequently in association with other neurocristopathies: Hirschsprung disease (HSCR) or congenital central hypoventilation syndrome (CCHS).
To the best of our knowledge, we report the first case of a child with CCHS and Hirschsprung disease who had a PHOX2B polyalanine-repeat-expansion mutation (PARM) (genotype 20/33) and developed high-risk neuroblastoma.
We report a CCHS case with presentation of hypoventilation during sleep and Hirschsprung disease; moreover, a genetic study of the patient confirmed the PHOX2B gene mutation as polyanaline stretch.
We report an infant with severe CCHS and Hirschsprung disease in whom, while awaiting genotyping, the diagnosis was facilitated by the results of a carbon dioxide (CO2) sensitivity study in the neonatal period and was confirmed by paired-like homeobox 2B (PHOX2B) mutational analysis.
Two main genes are involved: PHOX2B, observed in familial cases and frequently associated with other neurocristopathies (Ondine's and Hirschsprung's disease); and ALK, mostly in familial tumours.
The findings for HOXB5 and PHOX2B provide supportive evidence that genes regulating ENCC proliferation, migration and differentiation could be risk factors for HSCR.
Germline PHOX2B alterations were also recently discovered in neuroblastoma cases with CCHS and/or Hirschsprung disease, but a comprehensive survey for mutational frequency and functional consequence has not been performed.
We recently identified the paired-like homeobox 2B (PHOX2B, MIM 603851) gene as disease-causing in dysautonomic disorders including Congenital Central Hypoventilation Syndrome (CCHS), Hirschsprung disease (HSCR) and NB in various combinations.
The syndromic HSCR entities studied were congenital central hypoventilation (CCHS) and Mowat-Wilson syndrome (MWS), caused by PHOX2B and ZFHX1B gene mutations, respectively.
Congenital central hypoventilation syndrome (CCHS), a unique disorder of respiratory control associated with Hirschsprung disease (HSCR) and tumors of neural crest origin, results from polyalanine repeat expansion mutations in the paired-like homeobox (PHOX)2B gene in more than 90% of cases, and alternative PHOX2B mutations in remaining cases.
On the basis of this indication, we screened three Italian families with recurrence of NB and one family with occurrence of ganglioneuroblastoma and isolated Hirschsprung disease for PHOX2B defects.
Recent studies have shown that 1) PHOX2B is the main disease-causing gene for congenital central hypoventilation syndrome, an autosomal dominant disorder with incomplete penetrance; 2) PHOX2B is the first gene for which germline mutations have been demonstrated to predispose to neuroblastoma; and 3) Hirschsprung disease was associated with an intronic single-nucleotide polymorphism of the PHOX2B gene in a case-control study.
Our four major findings are the extreme rarity of CCHS, the improved recognition over time, the lack of effect of HSCR on the mortality rate, and the high frequency of PHOX2B mutations.