Pseudoxanthoma elasticum

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Pseudoxanthoma elasticum (PXE) is a progressive disorder that is characterized by the accumulation of deposits of calcium and other minerals (mineralization) in elastic fibers. Elastic fibers are a component of connective tissue, which provides strength and flexibility to structures throughout the body.

In PXE, mineralization can affect elastic fibers in the skin, eyes, and blood vessels, and less frequently in other areas such as the digestive tract. People with PXE may have yellowish bumps called papules on their necks, underarms, and other areas of skin that touch when a joint bends (flexor areas). They may also have abnormalities in the eyes, such as a change in the pigmented cells of the retina (the light-sensitive layer of cells at the back of the eye) known as peau d'orange. Another eye abnormality known as angioid streaks occurs when tiny breaks form in the layer of tissue under the retina called Bruch's membrane. Bleeding and scarring of the retina may also occur, which can cause vision loss.

Mineralization of the blood vessels that carry blood from the heart to the rest of the body (arteries) may cause other signs and symptoms of PXE. For example, people with this condition can develop narrowing of the arteries (arteriosclerosis) or a condition called claudication that is characterized by cramping and pain during exercise due to decreased blood flow to the arms and legs. Rarely, bleeding from blood vessels in the digestive tract may also occur.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Mutations in the ABCC6 gene cause PXE. This gene provides instructions for making a protein called MRP6 (also known as the ABCC6 protein). This protein is found primarily in cells of the liver and kidneys, with small amounts in other tissues, including the skin, stomach, blood vessels, and eyes. MRP6 is thought to transport certain substances across the cell membrane; however, the substances have not been identified. Some studies suggest that the MRP6 protein stimulates the release of a molecule called adenosine triphosphate (ATP) from cells through an unknown mechanism. ATP can be broken down into other molecules, including adenosine monophosphate (AMP) and pyrophosphate. Pyrophosphate helps control deposition of calcium and other minerals in the body. Other studies suggest that a substance transported by MRP6 is involved in the breakdown of ATP. This unidentified substance is thought to help prevent mineralization of tissues.

Mutations in the ABCC6 gene lead to an absent or nonfunctional MRP6 protein. It is unclear how a lack of properly functioning MRP6 protein leads to PXE. This shortage may impair the release of ATP from cells. As a result, little pyrophosphate is produced, and calcium and other minerals accumulate in elastic fibers of the skin, eyes, blood vessels and other tissues affected by PXE. Alternatively, a lack of functioning MRP6 may impair the transport of a substance that would normally prevent mineralization, leading to the abnormal accumulation of calcium and other minerals characteristic of PXE.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

PXE is inherited in an autosomal recessive manner, which means both copies of the gene in each cell have mutations. Most often, the parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but do not show signs and symptoms of the condition.

In a few cases, an affected individual has one affected parent and one parent without the signs and symptoms of the disorder. This situation resembles autosomal dominant inheritance, in which one copy of an altered gene in each cell is sufficient to cause a disorder and the mutation is typically inherited from one affected parent. In these cases of PXE, however, the parent without apparent symptoms has an ABCC6 gene mutation. The affected offspring inherits two altered genes, one from each parent. This appearance of autosomal dominant inheritance when the pattern is actually autosomal recessive is called pseudodominance.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

PXE affects approximately 1 in 50,000 people worldwide. For reasons that are unclear, this disorder is diagnosed twice as frequently in females as in males.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Abnormal cardiovascular system morphology · Very frequent (99-80%)

Any structural anomaly of the heart and blood vessels.

Abnormality of the cerebral vasculature · Very frequent (99-80%)

An anomaly of the cerebral blood vessels.

Abnormality of the skin · Very frequent (99-80%)

An abnormality of the skin.

Angioid streaks of the fundus · Very frequent (99-80%)

Irregular lines in the outer retina and Bruch membrane that are typically configured in a radiating fashion and emanate from the optic disc. Angioid streaks are crack-like dehiscences in abnormally thickened and calcified Bruch membrane, resulting in atrophy of the overlying retinal pigment epithelium. They may be associated with a number of endocrine, metabolic, and connective tissue abnormalities but can be idiopathic. They can be associated with neovascular complexes (choroid).

Arterial stenosis · Very frequent (99-80%)

Narrowing or constriction of the inner surface (lumen) of an artery.

Retinal hemorrhage · Very frequent (99-80%)

Bleeding located within the retina. Retinal hemorrhages range from the smallest dot and blot hemorrhage to massive sub-hyaloid hemorrhage.

Retinopathy · Very frequent (99-80%)

Any noninflammatory disease of the retina. This nonspecific term is retained here because of its wide use in the literature, but if possible new annotations should indicate the precise type of retinal abnormality.

Thickened nuchal skin fold · Very frequent (99-80%)

A thickening of the skin thickness in the posterior aspect of the fetal neck. A nuchal fold (NF) measurement is obtained in a transverse section of the fetal head at the level of the cavum septum pellucidum and thalami, angled posteriorly to include the cerebellum. The measurement is taken from the outer edge of the occiput bone to the outer skin limit directly in the midline. An NF measurement greater than 5 mm at 14 to 17+6 weeks of gestation, or 6 mm at 18 to 28 weeks has been associated with a markedly increased risk for Down syndrome.

Other findings in the same source

From: Orphanet

Additional reported features include Excessive wrinkled skin (Very frequent (99-80%)); Lack of skin elasticity (Very frequent (99-80%)); Bruising susceptibility (Frequent (79-30%)); Hyperpigmented papule (Frequent (79-30%)); Intermittent claudication (Frequent (79-30%)); Redundant skin (Frequent (79-30%)); Retinal peau d'orange (Frequent (79-30%)); Striae distensae (Frequent (79-30%)); Abnormal thorax morphology (Occasional (29-5%)); Abnormality of the endocardium (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Pseudoxanthoma elasticum is Dermatology, with a dermatologist as the relevant type of clinician. Dermatologist; paediatric services for children as appropriate.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which features of the skin, hair or nails distinguish the possibilities?
• Would photographs over time help document the changes?
• What should be expected from treatment, and how will irritation or other adverse effects be managed?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Pseudoxanthoma elasticum. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.