Pseudoxanthoma Elasticum (PXE)
Description
Pseudoxanthoma Elasticum (PXE) is a rare, inherited disorder that affects the connective tissue in the body. It primarily impacts the skin, eyes, and blood vessels. This condition causes the elastic fibers in these tissues to become brittle and break down, leading to a range of symptoms.
Genes Involved
PXE is caused by mutations in genes responsible for producing proteins involved in the regulation of elastic fiber formation. The most common gene associated with PXE is ABCC6. However, mutations in other genes, such as the ELN and ATP7B genes, have also been linked to the condition.
Recognizing the Signs and Symptoms
The hallmark of PXE is the appearance of yellowish, papular lesions on the skin, particularly in areas like the neck, armpits, and groin. These lesions may resemble small, raised bumps or folds. Other signs and symptoms can include:
- Eye problems: PXE can cause retinal detachment, angioid streaks (thin, linear cracks in the retina), and vision loss.
- Blood vessel problems: People with PXE may develop hardening and narrowing of arteries (atherosclerosis) in the legs, leading to pain or cramping during exercise (claudication).
- Gastrointestinal issues: Some individuals with PXE experience bleeding in the digestive system.
- Joint stiffness: In some cases, PXE can cause stiffness and pain in the joints.
Causes
PXE is an inherited disorder, meaning it is passed down through families. The condition is usually caused by a mutation in the ABCC6 gene, although other genes may also play a role. If one parent has PXE, there is a 50% chance of their child inheriting the condition. The exact cause of the genetic defect is unknown.
Inheritance/recurrence risk
PXE is typically inherited in an autosomal recessive pattern. This means that an individual must inherit two copies of the mutated gene, one from each parent, to develop the condition. If both parents carry the mutated gene, there is a 25% chance of their child inheriting two copies and developing PXE, a 50% chance of inheriting one copy and being a carrier without symptoms, and a 25% chance of inheriting neither copy and not developing the condition.
