Skip Navigation
Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed November 2007

What is the official name of the CRTAP gene?

The official name of this gene is “cartilage associated protein.”

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

What is the normal function of the CRTAP gene?

The CRTAP gene provides instructions for making a protein called cartilage associated protein. While the specific function of this protein is not known, it plays an important role in normal bone development. Cartilage associated protein works with two other proteins, leprecan and cyclophilin B, as part of a complex that helps process certain forms of collagen. Collagens are proteins that provide strength, support, and the ability to stretch (elasticity) to many body tissues.

The complex containing cartilage associated protein modifies a protein building block (amino acid) called proline in collagen molecules. This modification, which is known as proline 3-hydroxylation, appears to be critical for the normal folding and assembly of collagen. It also may be important for releasing collagen molecules into the spaces around cells (the extracellular matrix). The secretion of collagen from cells is necessary for the proper formation of connective tissues, such as bones, tendons, and cartilage, that form the body's supportive framework.

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

osteogenesis imperfecta - caused by mutations in the CRTAP gene

At least five mutations in the CRTAP gene are responsible for a rare type of osteogenesis imperfecta that is usually classified as type VII. Several of these mutations prevent cells from producing any cartilage associated protein. Without this protein, bones and other connective tissues do not form properly, leading to a very severe form of the disorder. Another mutation in the CRTAP gene greatly reduces the amount of cartilage associated protein produced, which disrupts the normal formation of collagen. This genetic change causes less severe signs and symptoms of osteogenesis imperfecta.

Where is the CRTAP gene located?

Cytogenetic Location: 3p22.3

Molecular Location on chromosome 3: base pairs 33,113,958 to 33,147,773

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The CRTAP gene is located on the short (p) arm of chromosome 3 at position 22.3.

The CRTAP gene is located on the short (p) arm of chromosome 3 at position 22.3.

More precisely, the CRTAP gene is located from base pair 33,113,958 to base pair 33,147,773 on chromosome 3.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about CRTAP?

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

You may also be interested in these resources, which are designed for genetics professionals and researchers.

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

  • cartilage-associated protein
  • CASP

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding CRTAP?

amino acid ; autosomal ; autosomal recessive ; cartilage ; collagen ; extracellular ; extracellular matrix ; gene ; mutation ; osteogenesis ; proline ; protein ; recessive ; secretion

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Barnes AM, Chang W, Morello R, Cabral WA, Weis M, Eyre DR, Leikin S, Makareeva E, Kuznetsova N, Uveges TE, Ashok A, Flor AW, Mulvihill JJ, Wilson PL, Sundaram UT, Lee B, Marini JC. Deficiency of cartilage-associated protein in recessive lethal osteogenesis imperfecta. N Engl J Med. 2006 Dec 28;355(26):2757-64. (
  • Labuda M, Morissette J, Ward LM, Rauch F, Lalic L, Roughley PJ, Glorieux FH. Osteogenesis imperfecta type VII maps to the short arm of chromosome 3. Bone. 2002 Jul;31(1):19-25. (
  • Marini JC, Cabral WA, Barnes AM, Chang W. Components of the collagen prolyl 3-hydroxylation complex are crucial for normal bone development. Cell Cycle. 2007 Jul 15;6(14):1675-81. Epub 2007 May 18. Review. (
  • Morello R, Bertin TK, Chen Y, Hicks J, Tonachini L, Monticone M, Castagnola P, Rauch F, Glorieux FH, Vranka J, Bächinger HP, Pace JM, Schwarze U, Byers PH, Weis M, Fernandes RJ, Eyre DR, Yao Z, Boyce BF, Lee B. CRTAP is required for prolyl 3- hydroxylation and mutations cause recessive osteogenesis imperfecta. Cell. 2006 Oct 20;127(2):291-304. (
  • NCBI Gene (
  • Tonachini L, Morello R, Monticone M, Skaug J, Scherer SW, Cancedda R, Castagnola P. cDNA cloning, characterization and chromosome mapping of the gene encoding human cartilage associated protein (CRTAP). Cytogenet Cell Genet. 1999;87(3-4):191-4. (
  • Ward LM, Rauch F, Travers R, Chabot G, Azouz EM, Lalic L, Roughley PJ, Glorieux FH. Osteogenesis imperfecta type VII: an autosomal recessive form of brittle bone disease. Bone. 2002 Jul;31(1):12-8. (


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.

Reviewed: November 2007
Published: February 8, 2016