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PXE is a genetic disease that causes fragmentation and mineralization of elastic fibers in some tissues.
It is a multisystem disease characterized by progressive calcification of tissue rich in elastic fibers.
Commonly involves the skin and eyes, and blood vessels in the form of premature atherosclerosis.
Caused by autosomal recessive mutations in the ABCC6 gene on the short arm of chromosome 16 (16p13.1)
Prevalence of pseudoxanthoma elasticum is about 1:25,000.
Females are twice as likely to be affected as males.
The disease occurs in all ethnicities
Afrikaners are more likely to have PXE
Yellowish slightly raised bumps characteristic of this condition.
Usually, pseudoxanthoma elasticum affects the skin first
Manifests often in childhood but frequently later.
In the calcification of the Bruch membrane associated with altered fundus reflex, and may result in retinal atrophy with vision loss.
Breaks in the calcified BRUCH membrane, angiod streaks, may develop into choroidal neovascularization.
Small, yellowish papular lesions form and cutaneous laxity mainly affects the neck, axillae, groin, and flexural creases,the inside parts of the elbows and knees
Skin may become lax and redundant.
Many individuals have diagonal grooves of the chin.
Affects the retina through a dimpling of the Bruch membrane only visible during ophthalmologic examinations.
Mineralization of the elastic fibers in the Bruch membrane create cracks visualized as angioid streaks, that radiate out from the optic nerve.
Angioid streaks are present almost all PXE patients and is usually appear a few years after the onset of cutaneous lesions.
These cracks allow small blood vessels to penetrate the retina, sometimes leading to retinal hemorrhages that may lead to the loss of central vision.
Vision loss is a major occurrence in many PXE patients.
It may affect the gastrointestinal and cardiovascular systems.
The main symptom of gastrointestinal involvement is bleeding, particularly from the stomach.:
Intermittent claudication is a prominent feature
At later stages coronary artery disease may develop, leading to angina and myocardial infarction
Pseudoxanthoma elasticum has an autosomal recessive pattern of inheritance.
80% of cases have detectable mutations in the ABCC6 gene.
Mutations in almost all parts of the gene have
Mutations in the gene include: missense, nonsense, splice alteration, insertion, small deletion or large deletion.
Inheritance is typically autosomal recessive.
Mutations in the ABCC6 gene codes for the MRP6 protein, which is expressed in most organs, but mainly in the liver and kidney.
Mutations in the ABCC6 gene is associated with premature atherosclerosis.
Mineralization and fragmentation of the elastin-containing fibers in connective tissue, the dermis, Bruch’s membrane and the midsized arteries.
It is hypothesized to be a metabolic disease, and clinical features related to the fact metabolites of vitamin K cannot reach peripheral tissues.
The diagnostic criteria: typical skin biopsy appearance and the presence of angioid streaks in the retina, with confirmation of the ABCC6 mutation.
No treatment interferes with the disease process, although dietary restriction of calcium has been tried with limited success.
For the growth of abnormal blood vessels in the retina, laser photocoagulation and photodynamic therapy may be used, as may antiangiogenis drugs.