PPI Supplementation to Fight ECtopIc Calcification in PXE

Using manufacturer dedicated software, the investigator, will determine the calcification score from CT images according to the validated Agatston score method. A threshold of 130 Hounsfield Units for calcium detection will be used for the study. Voxels above this threshold representing arterial wall calcifications will be manually identified and selected by the observer on the CT image. Calcifications mass in the studied arterial segments will be analyzed and quantified. The length and antero-posterior mean diameter of each arterial segment will be determined for further normalization of the calcification score to the arterial wall surface (data expressed as HU/mm2 of arterial surface). The intraclass correlation and Bland-Altman coefficient for inter-observer reliability of the total peripheral artery calcium mass measurement will be determined by scoring 10 random scans by two independent investigators.

number of patient with dematological changes. Dermatological changes will be monitored by a dermatoscopic study of the skin according to the following protocol: Images will be acquired from commonly affected areas (neck, axilla, antecubital fossae, armpits and periumbilical area) by a contact dermatoscope (SD) with non-polarized light and recorded, as previously described .

The investigators will ensure that the very same areas are imaged at baseline and at the end of the study. The surface of SD elementary changes featuring yellow papulae (presenting as "dots" or "reticular networks") on digitized images will be compared using an open image processing software (ImageJ, https://imagej.nih.gov/ij/index.html NIH).

Number of patietns with ophtalmologic changes. These changes will be monitored (blinded to treatment) by the occurrence of subretinal neovascularization events, the frequency of anti-VEGF administration and the best-corrected visual acuity (BCVA). A sub-retinal neovascularization event will be defined as any of the following that provide an indication to start or intensify anti-VEGF injections to prevent (further) visual impairment: 1) retinal bleeding suspected to be caused by sub-retinal neovascularization (if needed confirmed by fluorescein angiography); 2) a significant increase in sub retinal or intraretinal fluid; and/or 3) growth of a sub retinal neovascular complex. These events will be scored by the trained ophthalmologist of the PXE reference center (Dr Th Bresson) who will be blinded for the treatment.

Ankle Brachial Index (ABI) at rest: Systolic arterial blood pressure will be recorded using a pneumatic cuff wrapped around the ankle. An ultrasound probe allows recording the blood flow in the left and right ankle arteries (namely posterior and anterior tibial arteries) and brachial arteries supine at rest. The ABI is determined by the ratio between the lowest ankle artery pressure and the highest brachial artery blood pressure.

A peripheral arterial occlusive disease (PAOD) is defined according to the actual recommendations: an ABI <0.90) and an incompressible arterial wall reflecting mediacalcosis defined by ABI>1.40.