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The official name of this gene is “paired-like homeobox 2a.”
PHOX2A is the gene's official symbol. The PHOX2A gene is also known by other names, listed below.
The PHOX2A gene provides instructions for making a protein that is found in the nervous system. This protein acts early in development to help promote the formation of nerve cells (neurons) and regulate the process by which the neurons mature to carry out specific functions (differentiation).
Most of researchers' knowledge about the PHOX2A protein comes from studies in other animals. From these studies, it is clear that the protein plays a critical role in the development of the autonomic nervous system, which controls involuntary body functions such as breathing, blood pressure, heart rate, and digestion. The PHOX2A protein is also involved in the formation of certain nerves in the head and face. Specifically, it appears to be critical for the development and function of cranial nerves III and IV, which emerge from the brain and control many of the muscles that surround the eyes (extraocular muscles). These muscles direct eye movement and determine the position of the eyes.
The PHOX2A gene belongs to a family of genes called homeobox (homeoboxes).
A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genefamilies) in the Handbook.
At least four mutations in the PHOX2A gene can cause congenital fibrosis of the extraocular muscles. These mutations are responsible for a form of the disorder called CFEOM2, which has been identified in several families of Middle Eastern descent.
Most of the mutations that cause congenital fibrosis of the extraocular muscles result in the production of an abnormally short, nonfunctional version of the PHOX2A protein. In humans, a lack of this protein prevents the normal development of several cranial nerves and the extraocular muscles they control. Abnormal development and function of these muscles leads to the characteristic features of the disorder, including restricted eye movement and related problems with vision. Although the PHOX2A protein plays an important role in autonomic nervous system development, PHOX2A mutations do not seem to affect the function of this part of the nervous system.
Cytogenetic Location: 11q13.2
Molecular Location on chromosome 11: base pairs 72,239,076 to 72,244,175
The PHOX2A gene is located on the long (q) arm of chromosome 11 at position 13.2.
More precisely, the PHOX2A gene is located from base pair 72,239,076 to base pair 72,244,175 on chromosome 11.
See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genelocation) in the Handbook.
You and your healthcare professional may find the following resources about PHOX2A helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
autonomic nervous system ; congenital ; cranial nerves ; differentiation ; digestion ; extraocular muscles ; fibrosis ; gene ; homeobox ; homeodomain ; involuntary ; mesoderm ; nervous system ; protein
You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://ghr.nlm.nih.gov/glossary).
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.