About Klippel-Trénaunay-Weber Syndrome
The New York Center for Rare Diseases supports the mission and guidelines of the Genetic and Rare Diseases Information Center (GARD). The following information is provided by the NIH.
Summary
Angioosteohypertrophic syndrome, also known as Klippel-Trénaunay-Weber syndrome, is a syndrome that affects the development of blood vessels, soft tissues, and bones. This syndrome has three characteristic features: a red birthmark called a port-wine stain, overgrowth of soft tissues and bones, and vein malformations such as varicose veins or malformations of deep veins in the limbs. The overgrowth of bones and soft tissues usually begins in infancy and most often only affects one leg. However, it can also affect the arms or sometimes the upper body area (torso). The overgrowth can cause pain, a feeling of heaviness, and make the affected leg (or arm) hard to move. Most, if not all, cases of angioosteohypertrophic syndrome are caused by somatic genetic changes in the PIK3CA gene.
Causes
What Causes This Disease?
Genetic Mutations: Angioosteohypertrophic syndrome is caused by genetic mutations, also known as pathogenic variants. Genetic mutations can be hereditary, when parents pass them down to their children, or they may occur randomly when cells are dividing. Genetic mutations may also result from contracted viruses, environmental factors, such as UV radiation from sunlight exposure, or a combination of any of these.
If you suspect you may have this disease, you may want to start collecting your family health history. Information such as other family members who have had similar symptoms, when their/your symptoms first appeared, or exposures to any potential disease-causing environmental factors should be discussed with your medical team.
Can This Disease Be Passed Down From Parent to Child?
Yes. It is possible for a biological parent to pass down genetic mutations that cause or increase the chances of getting this disease to their child. This is known as inheritance. Knowing whether other family members have previously had this disease, also known as family health history, can be very important information for your medical team.
There are multiple ways, or patterns, a disease can be inherited depending on the gene(s) involved. Based on GARD’s current data, this disease can be inherited in the following pattern(s):
Autosomal Dominant: Autosomal means the gene involved is located on one of the numbered chromosomes. Dominant means that a child only needs to inherit one copy of the mutated gene, from either biological parent, to be affected by the disease.
People affected by an autosomal dominant disease have a 50% chance of passing on the mutated gene to their biological child.