Capillary malformation-arteriovenous malformation syndrome
Capillary malformation-arteriovenous malformation syndrome (CM-AVM) is a vascular disorder characterized by skin-surface capillary malformations and, in some cases, more serious arteriovenous abnormalities.
Overview
Capillary malformation-arteriovenous malformation syndrome (CM-AVM) is a disorder of the vascular system, the body's complex network of blood vessels. The system includes arteries (carrying oxygen-rich blood from the heart), veins (carrying blood back to the heart), and capillaries (tiny vessels connecting arteries and veins).
Symptoms
The condition is characterized by capillary malformations (CMs), which are enlarged capillaries that increase blood flow near the skin's surface. These appear as small, round, pink or red spots, typically on the face, arms, and legs. They may be present at birth or develop during childhood and generally do not cause health problems on their own.
Some individuals also develop more serious vascular abnormalities, including:
- Arteriovenous malformations (AVMs)
- Arteriovenous fistulas (AVFs)
These are abnormal connections between arteries, veins, and capillaries that affect circulation. Depending on their location, they can lead to complications such as:
- Abnormal bleeding
- Migraine headaches
- Seizures
- Heart failure
While these complications can be life-threatening, some individuals with these vascular abnormalities never experience symptoms.
Causes & Risk Factors
CM-AVM is caused by mutations in the RASA1 gene. This gene provides instructions for making the protein p120-RasGAP, which is essential for transmitting chemical signals that control cell growth, division, differentiation, and movement. It appears to be vital for the normal development of the vascular system.
Mutations lead to a nonfunctional version of the protein, disrupting chemical signaling during development, though the exact mechanism leading to specific vascular abnormalities remains unclear.
Inheritance
This condition is inherited in an autosomal dominant pattern, meaning one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, the mutation is inherited from a parent, though some cases result from new mutations in people with no family history of the disorder.