After we have already reported basics about orphan diseases, we want to focus on some of them and go more into detail, starting with Pseudoxanthoma elasticum (PXE). Disclaimer: Since we just touch on some facts in this article, more in-depth information and contacts for affected patients can be found here: https://www.pxe.org/overview
PXE is an inherited disorder, involves degeneration of the elastic fibers and is inherited from the parents. It typically causes abnormalities in the skin, eyes, cardiovascular as well as cerebral vascular and gastrointestinal system. PXE was recognized over a hundred years ago, but yet remains difficult to diagnose since there are few affected patients and many do not know about the disease and its symptoms. The onset of the disease may appear at any age, typically starts in adolescence with skin abnormalities. PXE is a rare disease with an estimation range from 1 to 1000.000 people to 1 in 25.000 people, yet some individuals affected are not yet (and may never be) diagnosed.
But what is PXE?
PXE causes calcification, meaning the accumulation of calcium and other minerals, in elastic fibers causing the fragmentation of elastic tissues. As we pointed out in our previous articles, Elastin as one of the major structural molecules (next to collagen) and normally has the capability of stretching and returning to its original length like a rubber band. Thereby it provides elasticity and flexibility to organs such as the skin and vessels. A calcification in elastic tissues and the degradation of elastic fibers impairs the proper function of the affected organs.
What are symptoms of PXE?
Symptoms depend on the affected area. Typical symptoms and most likely first diagnosed are yellow-white small raised areas in the skin folds, resulting from fragmented and calcified elastin fibers in the dermis. While those skin abnormalities frequently appear in the neck, armpits, and other areas that bend, often the eye is affected too. It is showing abnormalities in the back of the eye (retinae) called angioid streaks, which are tiny breaks in the elastin-filled tissue there, causing reduced vision. Besides that, it shows that PXE also affects the cardiovascular system as it causes mineralization in the mid-laminar layer of medium-sized arteries. This then causes the narrowing of blood vessels causing premature arteriosclerosis with subsequent claudication (patients suffer from cramping pain in the legs during exercise), hypertension, and myocardial infarction. Additionally, the heart can be affected by atherosclerosis and mitral valve prolapse. Gastrointestinal bleedings are rare symptoms.
How is PXE inherited?
From the parents, either as an autosomal recessive or as an autosomal dominant trait. It is caused by the mutation of the ABCC6 gene. Therefore, PXE is not contagious, but an inherited disorder of elastin.
How is PXE diagnosed?
Clinical diagnosis involves two main symptoms, the detection of skin abnormalities and the presence of angioid streaks in the retina. Additional genetic testing of mutations in the ABCC6 gene confirms the diagnosis.
Treatments and Outlook
As there is no cure for PXE, yet the only treatments are monitoring organ functions and the treatment of symptoms resulting from the effects of the weakened elastin fibers. Patients should find specialized healthcare professionals, since there are few well-informed professionals.
That is where our technology platform DESTiNED comes into place and will hopefully help those, suffering from orphan indications such as PXE.
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