Reviewed April 2006
What is the official name of the PAX3 gene?
The official name of this gene is “paired box 3.”
PAX3 is the gene's official symbol. The PAX3 gene is also known by other names, listed below.
What is the normal function of the PAX3 gene?
The PAX3 gene belongs to a family of genes that plays a critical role in the formation of tissues and organs during embryonic development. The PAX gene family is also important for maintaining the normal function of certain cells after birth. To carry out these roles, the PAX genes provide instructions for making proteins that attach to specific areas of DNA. By attaching to critical DNA regions, these proteins help control the activity of particular genes. On the basis of this action, PAX proteins are called transcription factors.
During embryonic development, the PAX3 gene is active in cells called neural crest cells. These cells migrate from the developing spinal cord to specific regions in the embryo. The protein made by the PAX3 gene directs the activity of other genes (such as MITF) that signal neural crest cells to form specialized tissues or cell types such as limb muscles, bones in the face and skull (craniofacial bones), some nerve tissue, and pigment-producing cells called melanocytes. Melanocytes produce the pigment melanin, which contributes to hair, eye, and skin color. Melanocytes are also found in certain regions of the brain and inner ear.
Does the PAX3 gene share characteristics with other genes?
The PAX3 gene belongs to a family of genes called PAX (paired box gene).
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? in the Handbook.
How are changes in the PAX3 gene related to health conditions?
-
Waardenburg syndrome - caused by mutations in the PAX3 gene
-
Several PAX3 mutations have been identified in people with Waardenburg syndrome, types I and III. Some of these mutations change one of the chemical building blocks (amino acids) used to make the PAX3 protein. Other mutations lead to an abnormally small version of the PAX3 protein. Researchers believe that all PAX3 mutations have the same effect; they destroy the ability of the PAX3 protein to bind to DNA and regulate the activity of other genes. As a result, melanocytes do not develop in certain areas of the skin, hair, eyes, and inner ear, leading to hearing loss and the patchy loss of pigmentation that are characteristic features of Waardenburg syndrome. Additionally, loss of PAX3 protein function disrupts development of craniofacial bones and certain muscles, producing the limb and facial features that are unique to Waardenburg syndrome, types I and III.
- cancers - associated with the PAX3 gene
-
Alterations in the activity of the PAX3 gene are associated with some cases of cancer of muscle tissue (alveolar rhabdomyosarcoma) that occur mainly in adolescents and young adults. Gene activity is altered when the PAX3 gene on chromosome 2 is fused with the FOXO1A gene (also called FKHR) on chromosome 13. This fusion event occurs when segments of chromosomes 2 and 13 are rearranged in certain cells that develop into muscle tissue. The fused PAX3-FOXO1A gene may enhance changes that can lead to cancer, such as uncontrolled cell division and cell growth.
- other disorders - caused by mutations in the PAX3 gene
-
One PAX3 mutation has been identified in individuals with a condition called craniofacial-deafness-hand syndrome. This condition is characterized by distinct facial features such as widely spaced eyes (hypertelorism) and a small nose, profound hearing loss, and hand abnormalities that affect the fingers and wrist. The mutation replaces the amino acid aspartic acid with the amino acid lysine at position 47 in the PAX3 protein (written as Asp47Lys). This mutation appears to affect the ability of the PAX3 protein to bind to DNA. As a result, the PAX3 protein does not function properly in neural crest cells, disrupting the development of craniofacial bones, the inner ear, and limb muscles.
Where is the PAX3 gene located?
Cytogenetic Location: 2q35-q37
Molecular Location on chromosome 2: base pairs 222,772,850 to 222,871,943
The PAX3 gene is located on the long (q) arm of chromosome 2 between positions 35 and 37.
More precisely, the PAX3 gene is located from base pair 222,772,850 to base pair 222,871,943 on chromosome 2.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about PAX3?
You and your healthcare professional may find the following resources about PAX3 helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
- PubMed
- Recent literature
-
OMIM - Genetic disorder catalog (3 links)
-
What other names do people use for the PAX3 gene or gene products?
- CDHS
- HUP2
- paired box gene 3 (Waardenburg syndrome 1)
- paired box homeotic gene 3
- paired domain gene 3
- paired domain gene HuP2
- PAX3/FKHR fusion gene
- PAX3_HUMAN
- WS1
Where can I find general information about genes?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding PAX3?
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? in the Handbook.