|http://ghr.nlm.nih.gov/ A service of the U.S. National Library of Medicine®|
The official name of this gene is “calpain 3, (p94).”
CAPN3 is the gene's official symbol. The CAPN3 gene is also known by other names, listed below.
The CAPN3 gene provides instructions for making an enzyme called calpain-3, which is found within muscle cells in structures called sarcomeres. Sarcomeres are the basic unit of muscle contraction. They are made of proteins that generate the mechanical force needed for muscles to contract.
The function of the calpain-3 enzyme is not well understood. Researchers suggest it may help cut (cleave) damaged proteins into shorter segments to facilitate their removal from the sarcomere. Studies have also shown that calpain-3 attaches (binds) to proteins involved in controlling the ability of muscle fibers to stretch (elasticity) and in cell signaling. However, its specific roles in these processes are unknown.
More than 300 mutations in the CAPN3 gene have been identified in people with limb-girdle muscular dystrophy type 2A. This form of limb-girdle muscular dystrophy is also called calpainopathy.
Limb-girdle muscular dystrophy is a group of related disorders characterized by muscle weakness and wasting, particularly in the shoulders, hips, and limbs. CAPN3 gene mutations are the most common cause of limb-girdle muscular dystrophy. These mutations account for approximately 30 percent of limb-girdle muscular dystrophy cases overall, although the percentage varies by specific population.
Most CAPN3 gene mutations change one protein building block (amino acid) in the calpain-3 enzyme. These mutations result in a calpain-3 enzyme that is abnormally short or unstable. Disruption of the enzyme's ability to properly cleave proteins for removal from the sarcomere may allow these waste proteins to accumulate in muscle tissue and become toxic. Other mechanisms have also been suggested to account for the muscle damage that underlies limb-girdle muscular dystrophy in people with CAPN3 gene mutations.
Cytogenetic Location: 15q15.1
Molecular Location on chromosome 15: base pairs 42,359,499 to 42,412,316
The CAPN3 gene is located on the long (q) arm of chromosome 15 at position 15.1.
More precisely, the CAPN3 gene is located from base pair 42,359,499 to base pair 42,412,316 on chromosome 15.
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 CAPN3 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.
amino acid ; calcium ; cell ; contraction ; enzyme ; gene ; muscular dystrophy ; population ; protease ; protein ; proteinase ; sarcomere ; subunit ; tissue ; toxic ; wasting
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.