Pseudoxanthoma Elasticum

What is pseudoxanthoma elasticum?

Pseudoxanthoma elasticum is a progressive disorder that affects connective tissue, the material that supports and holds together different structures of the body. This condition is characterised by accumulated deposits of calcium (calcification) and other minerals in elastic fibers, a component of connective tissue.

Calcification can affect elastic fibers in the skin, eyes, and blood vessels, and less frequently in other areas such as the digestive tract. As a result, people with pseudoxanthoma elasticum may have yellowish bumps (papules) on their necks, underarms, and elsewhere on the skin. They also may have changes in the eye called angioid streaks, which occur in the layer of cells that are sensitive to light (retina). Angioid streaks can lead to bleeding and scarring of the retina, which can cause vision loss.

Additional problems may arise if blood vessels stiffen and lose their flexibility due to calcification. People with pseudoxanthoma elasticum are at increased risk for problems such as high blood pressure (hypertension) and decreased blood flow to the arms and legs that causes cramping or pain with exercise (claudication). Bleeding from blood vessels in the digestive tract and other tissues may also occur.

How common is pseudoxanthoma elasticum?

The estimated prevalence of pseudoxanthoma elasticum ranges from 1 in 25,000 to 1 in 100,000 individuals. The true prevalence is probably higher because mildly affected people are often not diagnosed. For reasons that are unknown, this disorder is diagnosed twice as frequently in females as in males.

What genes are related to pseudoxanthoma elasticum?

Mutations in the ABCC6 gene cause pseudoxanthoma elasticum.

Little is known about the function of the ABCC6 gene. It provides instructions for making a protein that probably transports certain substances across the cell membrane. Mutations in the ABCC6 gene lead to an absent or nonfunctional protein, which may impair the transport of substances and disrupt normal cell activities. It remains unclear how ABCC6 mutations lead to calcification of elastic fibers and the characteristic features of pseudoxanthoma elasticum.

How do people inherit pseudoxanthoma elasticum?

Pseudoxanthoma elasticum is inherited in an autosomal recessive manner, which means two copies of the gene in each cell must be altered for a person to be affected by the disorder. Most often, the parents of a person with pseudoxanthoma elasticum are carriers of one copy of the altered gene but do not show signs and symptoms of the disorder.

In a few cases, an affected individual has one affected parent and one parent with a normal appearance. This situation is called pseudodominance because it resembles autosomal dominant inheritance, in which one copy of the altered gene is sufficient to cause the disorder. Such cases, however, are actually autosomal recessive because the normal-appearing parent carries an ABCC6 mutation. The affected offspring inherits two altered genes, one from each parent.

What other names do people use for pseudoxanthoma elasticum?

• Gronblad-Strandberg Syndrome
• PXE - Pseudoxanthoma elasticum