PHOX2B

Paired-like homeobox 2b (PHOX2B), also known as neuroblastoma Phox (NBPhox), is a is_associated_with::protein that in humans is encoded by the PHOX2B is_associated_with::gene located on chromosome 4.

It codes for a is_associated_with::homeodomain transcription factor. It is expressed exclusively in the nervous system, in most neurons that control the viscera (cardiovascular, digestive and respiratory systems). It is also required for their differentiation.

Pathology
Mutations in human PHOX2B cause a rare disease of the visceral nervous system (dysautonomia): is_associated_with::Ondine's curse or is_associated_with::Congenital Central Hypoventilation Syndrome (associated with respiratory arrests during sleep and, occasionally, wakefulness), is_associated_with::Hirschprung's disease (partial agenesis of the is_associated_with::enteric nervous system), is_associated_with::ROHHAD, and tumours of the is_associated_with::sympathetic ganglia. In most people, Exon 3 of the gene contains a sequence of 20 polyalanine repeats. An increase in the number of repeats is associated with congenital central hypoventilation syndrome. There may also be other pathogenic mutations further along the gene.