PHOX2B
Encyclopedia
Paired-like homeobox 2b (PHOX2B), also known as neuroblastoma Phox (NBPhox), is a protein
that in humans is encoded by the PHOX2B gene
located on chromosome 4
.
It codes for a 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.
or Congenital Central Hypoventilation Syndrome (CCHS, associated with respiratory arrests during sleep and, occasionally, wakefulness), Hirschprung's disease (partial agenesis of the enteric nervous system
) and tumours of the sympathetic ganglia
.
In most persons, 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 are other non-polyalanine repeats that may also be involved, as well as other mutations of uncertain significance during gene sequencing.
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
that in humans is encoded by the PHOX2B gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
located on chromosome 4
Chromosome 4 (human)
125px|rightChromosome 4 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 4 spans more than 186 million base pairs and represents between 6 and 6.5 percent of the total DNA in cells.Identifying genes on each chromosome is an active area...
.
It codes for a 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 (or dysautonomia): Ondine's curseOndine's curse
Ondine's Curse, also called congenital central hypoventilation syndrome or primary alveolar hypoventilation, is a respiratory disorder that is fatal if untreated...
or Congenital Central Hypoventilation Syndrome (CCHS, associated with respiratory arrests during sleep and, occasionally, wakefulness), Hirschprung's disease (partial agenesis of the enteric nervous system
Enteric nervous system
The enteric nervous system is a subdivision of the autonomic nervous system that directly controls the gastrointestinal system in vertebrates.It is derived from neural crest.-Function:...
) and tumours of the sympathetic ganglia
Sympathetic ganglia
Sympathetic ganglia are the ganglia of the sympathetic nervous system. They deliver information to the body about stress and impending danger, and are responsible for the familiar fight-or-flight response. They contain approximately 20000–30000 nerve cell bodies and are located close to and...
.
In most persons, 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 are other non-polyalanine repeats that may also be involved, as well as other mutations of uncertain significance during gene sequencing.