Pseudoxanthoma elasticum

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Pseudoxanthoma Elasticum (PXE) is a genetic disease that is caused by autosomal recessive mutations in the ABCC6 gene on the short arm of chromosome 16. PXE causes mineralization of some elastic fibers. The most common problems arise in the skin and eyes.

Usually, PXE affects skin first. Small, yellowish papular lesions form and cutaneous laxity mainly affects the neck, axillae (armpit), groin, and flexural creases (Gheduzzi et al. 2003). Skin may become lax and redundant.

PXE first affects the retina through a dimpling of the Bruch membrane (a thin membrane separating the blood vessel-rich layer from the pigmented layer of the retina), that is only visible during ophthalmologic examinations. This is called peau d’orange (a French term meaning that the retina resembles the skin of an orange). Eventually the mineralization of the elastic fibers in the Bruch membrane create cracks called angioid streaks. They radiate out from the optic nerve. This symptom is present almost all PXE patients and is usually noticed a few years after the onset of cutaneous lesions. These cracks may allow small blood vessels that were originally held back by Bruch's membrane to penetrate the retina. These blood vessels sometimes leak, and it's these retinal hemorrhages that may lead to the loss of central vision (Glass 2005). Angioid streaks do not cause distortion of vision, even if they cross into the foveal area.

PXE may affect the cardiovascular and gastrointestinal systems. Cardiovascular problems include hypertension due to renovascular disease, coronary artery disease, and mitral valve incompetence.

All individuals affected by PXE have peau d'orange and angioid streaks and most have lesional skin in the flexor areas. Many also have intermittent claudication.

Treatment options involve plastic surgery, laser surgey for retinal disease, and medication or (in rare cases) angioplasty to address circulation problems.

PXE has the distinction of being the only disease for which a lay person is the inventor of the gene, ABCC6. Sharon F. Terry, co-founder of PXE International with her husband, Patrick F. Terry, worked with scientists to discover and patent the gene in 2000. The Terrys' two children have pseudoxanthoma elasticum.

[edit] References

Terry, SF and Bercovitch, LB 2004. (1 December 2005). So now that you’ve found the gene, what comes next?. PXE International, Inc. (http://www.pxe.org/virtpat/docs/genetics/genesequel.html) accessed 1 December 2005.
Gheduzzi, D., R. Sammarco, D. Quaglino, L. Bercovitch, S. Terry, W. Taylor, and I. P. Ronchetti. 2003. Extracutaneous ultrastructural alterations in pseudoxanthoma elasticum. U. Pathology. 27: 375-384.