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Genetics Home Reference: your guide to understanding genetic conditions
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Capillary malformation-arteriovenous malformation syndrome

(often shortened to CM-AVM)
Reviewed August 2011

What is CM-AVM?

Capillary malformation-arteriovenous malformation syndrome (CM-AVM) is a disorder of the vascular system, which is the body's complex network of blood vessels. The vascular system consists of arteries, which carry oxygen-rich blood from the heart to the body's various organs and tissues; veins, which carry blood back to the heart; and capillaries, which are tiny blood vessels that connect arteries and veins.

CM-AVM is characterized by capillary malformations (CMs), which are composed of enlarged capillaries that increase blood flow near the surface of the skin. These malformations look like multiple small, round, pink or red spots on the skin. In most affected individuals, capillary malformations occur on the face, arms, and legs. These spots may be visible from birth or may develop during childhood. By themselves, capillary malformations usually do not cause any health problems.

In some people with CM-AVM, capillary malformations are the only sign of the disorder. However, other affected individuals also have more serious vascular abnormalities known as arteriovenous malformations (AVMs) and arteriovenous fistulas (AVFs). AVMs and AVFs are abnormal connections between arteries, veins, and capillaries that affect blood circulation. Depending on where they occur in the body, these abnormalities can be associated with complications including abnormal bleeding, migraine headaches, seizures, and heart failure. In some cases the complications can be life-threatening. In people with CM-AVM, complications of AVMs and AVFs tend to appear in infancy or early childhood; however, some of these vascular abnormalities never cause any symptoms.

Some vascular abnormalities seen in CM-AVM are similar to those that occur in a condition called Parkes Weber syndrome. In addition to vascular abnormalities, Parkes Weber syndrome usually involves overgrowth of one limb. CM-AVM and some cases of Parkes Weber syndrome have the same genetic cause.

How common is CM-AVM?

CM-AVM is thought to occur in at least 1 in 100,000 people of northern European origin. The prevalence of the condition in other populations is unknown.

What genes are related to CM-AVM?

CM-AVM is caused by mutations in the RASA1 gene. This gene provides instructions for making a protein known as p120-RasGAP, which is involved in transmitting chemical signals from outside the cell to the nucleus. These signals help control several important cell functions, including cell growth and division (proliferation), the process by which cells mature to carry out specific functions (differentiation), and cell movement. The role of the p120-RasGAP protein is not fully understood, although it appears to be essential for the normal development of the vascular system.

Mutations in the RASA1 gene lead to the production of a nonfunctional version of the p120-RasGAP protein. A loss of this protein's activity disrupts tightly regulated chemical signaling during development. However, it is unclear how these changes lead to the specific vascular abnormalities seen in people with CM-AVM.

Related Gene(s)

Changes in this gene are associated with capillary malformation-arteriovenous malformation syndrome.

  • RASA1

How do people inherit CM-AVM?

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.

In most cases, an affected person inherits the mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family.

Where can I find information about diagnosis or management of CM-AVM?

These resources address the diagnosis or management of CM-AVM and may include treatment providers.

  • Gene Review: RASA1-Related Disorders (http://www.ncbi.nlm.nih.gov/books/NBK52764)
  • Genetic Testing Registry: Capillary malformation-arteriovenous malformation (http://www.ncbi.nlm.nih.gov/gtr/conditions/C1842180)

You might also find information on the diagnosis or management of CM-AVM in Educational resources (http://www.ghr.nlm.nih.gov/condition/capillary-malformation-arteriovenous-malformation-syndrome/show/Educational+resources) and Patient support (http://www.ghr.nlm.nih.gov/condition/capillary-malformation-arteriovenous-malformation-syndrome/show/Patient+support).

General information about the diagnosis (http://ghr.nlm.nih.gov/handbook/consult/diagnosis) and management (http://ghr.nlm.nih.gov/handbook/consult/treatment) of genetic conditions is available in the Handbook. Read more about genetic testing (http://ghr.nlm.nih.gov/handbook/testing), particularly the difference between clinical tests and research tests (http://ghr.nlm.nih.gov/handbook/testing/researchtesting).

To locate a healthcare provider, see How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.

Where can I find additional information about CM-AVM?

You may find the following resources about CM-AVM helpful. These materials are written for the general public.

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

What other names do people use for CM-AVM?

  • capillary malformation-arteriovenous malformation

For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines (http://ghr.nlm.nih.gov/ConditionNameGuide) and How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.

What if I still have specific questions about CM-AVM?

Ask the Genetic and Rare Diseases Information Center (http://rarediseases.info.nih.gov/GARD/).

What glossary definitions help with understanding CM-AVM?

arteries ; arteriovenous ; autosomal ; autosomal dominant ; capillaries ; cell ; cM ; congenital ; differentiation ; gene ; heart failure ; inherited ; malformation ; migraine ; mutation ; nucleus ; oxygen ; prevalence ; proliferation ; protein ; RAS ; sign ; syndrome ; vascular ; veins

You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.ghr.nlm.nih.gov/glossary).

References

  • Boon LM, Mulliken JB, Vikkula M. RASA1: variable phenotype with capillary and arteriovenous malformations. Curr Opin Genet Dev. 2005 Jun;15(3):265-9. Review. (http://www.ncbi.nlm.nih.gov/pubmed/15917201?dopt=Abstract)
  • Eerola I, Boon LM, Mulliken JB, Burrows PE, Dompmartin A, Watanabe S, Vanwijck R, Vikkula M. Capillary malformation-arteriovenous malformation, a new clinical and genetic disorder caused by RASA1 mutations. Am J Hum Genet. 2003 Dec;73(6):1240-9. Epub 2003 Nov 24. (http://www.ncbi.nlm.nih.gov/pubmed/14639529?dopt=Abstract)
  • Gene Review: RASA1-Related Disorders (http://www.ncbi.nlm.nih.gov/books/NBK52764)
  • Hershkovitz D, Bercovich D, Sprecher E, Lapidot M. RASA1 mutations may cause hereditary capillary malformations without arteriovenous malformations. Br J Dermatol. 2008 May;158(5):1035-40. doi: 10.1111/j.1365-2133.2008.08493.x. Epub 2008 Mar 20. (http://www.ncbi.nlm.nih.gov/pubmed/18363760?dopt=Abstract)
  • Revencu N, Boon LM, Mulliken JB, Enjolras O, Cordisco MR, Burrows PE, Clapuyt P, Hammer F, Dubois J, Baselga E, Brancati F, Carder R, Quintal JM, Dallapiccola B, Fischer G, Frieden IJ, Garzon M, Harper J, Johnson-Patel J, Labrèze C, Martorell L, Paltiel HJ, Pohl A, Prendiville J, Quere I, Siegel DH, Valente EM, Van Hagen A, Van Hest L, Vaux KK, Vicente A, Weibel L, Chitayat D, Vikkula M. Parkes Weber syndrome, vein of Galen aneurysmal malformation, and other fast-flow vascular anomalies are caused by RASA1 mutations. Hum Mutat. 2008 Jul;29(7):959-65. doi: 10.1002/humu.20746. (http://www.ncbi.nlm.nih.gov/pubmed/18446851?dopt=Abstract)

 

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.

 
Reviewed: August 2011
Published: December 22, 2014