Parkes Weber syndrome ... (Parkes Weber syndrome) - Gen RASA1.

Parkes Weber syndrome is a disorder of the vascular system characterized by capillary malformations and arteriovenous fistulas (AVF), which are present from birth. Capillary malformations increase blood flow near the skin surface. Usually they are seen as a large, flat, pink spots on the skin. In people with Parkes Weber syndrome, capillary malformations occur with multiple arteriovenous microfistulas, consisting of tiny abnormal connections between arteries and veins that affect blood circulation. These FAV may be associated with life - threatening complications, including bleeding and abnormal heart failure. Another feature of Parkes Weber syndrome is bone overgrowth and soft tissue of a limb, more often a leg. Some vascular abnormalities observed in Weber syndrome-Parkes are similar to a condition called capillary malformation syndrome - arteriovenous malformation (AVM-CM). CM-AVM and some cases of Parkes Weber syndrome have the same genetic cause.

Some cases of Parkes Weber syndrome are due to mutations in the gene RASA1, located on the long arm of chromosome 5 (5q13.3). When the disease is due to mutations in the gene RASA1, those affected usually have multiple capillary malformations. It is unlikely that people with Parkes Weber syndrome who have multiple capillary malformations have mutations in the gene RASA1. In these cases, the reason for the disease is often unknown.

The RASA1 gene encodes a protein known as p120-RasGAP, which is involved in the transmission of chemical signals from outside the cell to the cell nucleus. These signals help control several important cellular functions, including cell growth and proliferation, differentiation and cell movement. Although the function of the protein p120-RasGAP is not entirely clear, it seems to be essential for normal development of the vascular system.

Several mutations have been identified in the RASA1 gene in people with Parkes Weber syndrome. These genetic changes result encoding a nonfunctional version of p120-RasGAP protein. A loss of activity of this protein altered intensively regulating chemical signaling during development. However, it is unclear how these changes cause specific vascular anomalies and limb overgrowth seen in people with Parkes Weber syndrome.

Most cases of Parkes Weber syndrome occur in people with no history of disease in your family. They are described as sporadic. When Parkes Weber syndrome is due to mutations in the gene RASA1 sometimes it inherited from an affected parent. In these cases, the disease is an autosomal dominant inheritance, which means that a copy of the altered gene in each cell is sufficient to express the disease.

Tests in IVAMI: in IVAMI perform detection of mutations associated with Parkes Weber syndrome by complete PCR amplification of exons RASA1 gene, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).