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Reviewed December 2013

What is the official name of the ACP5 gene?

The official name of this gene is “acid phosphatase 5, tartrate resistant.”

ACP5 is the gene's official symbol. The ACP5 gene is also known by other names, listed below.

Read more about gene names and symbols on the About page.

What is the normal function of the ACP5 gene?

The ACP5 gene provides instructions for making an enzyme called tartrate-resistant acid phosphatase type 5 (TRAP). The TRAP enzyme primarily regulates the activity of a protein called osteopontin, which is produced in bone cells called osteoclasts and in immune cells. Osteopontin performs a variety of functions in these cells. Two versions (isoforms) of the TRAP enzyme are produced: TRAP5a is found primarily in immune cells and TRAP5b is found primarily in bone cells called osteoclasts.


In the immune system, osteopontin is found primarily in cells called macrophages and dendritic cells. The protein helps fight infection by promoting inflammation, regulating immune cell activity, and turning on various immune system cells that are necessary to fight off foreign invaders such as bacteria and viruses. Like TRAP5b in bone cells, the TRAP5a enzyme inactivates osteopontin in macrophages and dendritic cells when it is no longer needed.

How are changes in the ACP5 gene related to health conditions?

spondyloenchondrodysplasia with immune dysregulation - caused by mutations in the ACP5 gene

At least 10 mutations in the ACP5 gene have been found to cause spondyloenchondrodysplasia with immune dysregulation (SPENCDI). This condition is characterized by abnormalities in bone growth and immune system function. The ACP5 gene mutations that cause SPENCDI typically change single protein building blocks (amino acids) in the TRAP enzyme or result in the production of an abnormally short enzyme. These mutations affect both TRAP isoforms and impair or eliminate TRAP's ability to inactivate osteopontin. As a result, osteopontin is abnormally active, prolonging bone breakdown by osteoclasts and triggering abnormal inflammation and immune responses by immune cells.

In people with SPENCDI, increased bone breakdown contributes to the skeletal abnormalities, including irregularly shaped bones and short stature. An overactive immune system leads to increased susceptibility to autoimmune disorders, which occur when the immune system malfunctions and attacks the body's own tissues and organs. Immune system abnormalities also impair the body's normal response to harmful invaders, resulting in frequent infections. SPENCDI has several additional features, including movement disorders and intellectual disability, but it is unknown how changes in TRAP enzyme function lead to these other signs and symptoms.

Where is the ACP5 gene located?

Cytogenetic Location: 19p13.2

Molecular Location on chromosome 19: base pairs 11,574,659 to 11,578,985

The ACP5 gene is located on the short (p) arm of chromosome 19 at position 13.2.


More precisely, the ACP5 gene is located from base pair 11,574,659 to base pair 11,578,985 on chromosome 19.


Where can I find additional information about ACP5?

You and your healthcare professional may find the following resources about ACP5 helpful.


What other names do people use for the ACP5 gene or gene products?

  • tartrate-resistant acid ATPase
  • tartrate-resistant acid phosphatase type 5
  • TRAP
  • TrATPase

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 ACP5?

acids ; autoimmune ; bacteria ; bone remodeling ; breakdown ; cell ; dephosphorylation ; disability ; enzyme ; gene ; immune system ; infection ; inflammation ; isoforms ; phosphatase ; protein ; short stature ; stature ; susceptibility ; tissue


See also Understanding Medical Terminology.

References (6 links)



Reviewed: December 2013
Published: July 27, 2015