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The official name of this gene is “paired-like homeodomain 2.”
PITX2 is the gene's official symbol. The PITX2 gene is also known by other names, listed below.
The PITX2 gene provides instructions for making a protein that attaches (binds) to specific regions of DNA and regulates the activity of other genes. On the basis of this action, the PITX2 protein is called a transcription factor. The PITX2 gene is part of a family of homeobox genes, which act during early embryonic development to control the formation of many parts of the body.
The PITX2 protein plays a critical role in early development, particularly in the formation of structures in the front part of the eye (the anterior segment). These structures include the colored part of the eye (the iris), the central hole in the iris through which light enters the eye (the pupil), and the clear front covering of the eye (the cornea). Studies suggest that the PITX2 protein also has functions in the adult eye, such as helping cells respond to oxidative stress. Oxidative stress occurs when unstable molecules called free radicals accumulate to levels that can damage or kill cells.
The PITX2 protein is also involved in the normal development of other parts of the body, including the teeth, heart, and abdominal organs.
The PITX2 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.
More than 45 mutations in the PITX2 gene have been found to cause Axenfeld-Rieger syndrome type 1, a condition that affects the development of the anterior segment of the eye and other parts of the body. Most PITX2 gene mutations reduce the amount of functional PITX2 protein that is produced in cells. However, some genetic changes (such as a duplication of the PITX2 gene) increase the amount or function of the PITX2 protein. Having either too little or too much of this protein disrupts the regulation of other genes needed for normal development.
Eye development appears to be the most sensitive to changes in PITX2 protein activity, which is why abnormalities of the anterior segment of the eye are the predominant features of Axenfeld-Rieger syndrome. However, changes in the amount of PITX2 protein can also lead to distinctive facial features, tooth abnormalities, and problems with development of other parts of the body in people with this condition.
Mutations in the PITX2 gene have also been identified in rare cases of several other eye disorders. Like Axenfeld-Rieger syndrome, these conditions primarily involve the anterior segment of the eye. They include Peters anomaly, which is a developmental condition characterized by thinning and clouding of the cornea, and ring dermoid of the cornea, a condition associated with tumor-like growths on the cornea. Mutations in the PITX2 gene have also been found in a few people with iris hypoplasia or iridogoniodysgenesis type 2, conditions that cause underdevelopment of the iris. Iridogoniodysgenesis type 2 is also associated with an elevated risk of increased pressure in the eye (glaucoma).
Cytogenetic Location: 4q25
Molecular Location on chromosome 4: base pairs 111,538,578 to 111,563,278
The PITX2 gene is located on the long (q) arm of chromosome 4 at position 25.
More precisely, the PITX2 gene is located from base pair 111,538,578 to base pair 111,563,278 on chromosome 4.
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 PITX2 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.
anterior ; cornea ; DNA ; duplication ; embryonic ; free radicals ; gene ; glaucoma ; homeobox ; homeodomain ; hypoplasia ; oxidative stress ; protein ; pupil ; stress ; syndrome ; transcription ; transcription factor ; tumor
You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.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.