**Pseudoxanthoma Elasticum, Kidney Stones and Pyrophosphate: From a Rare Disease to Urolithiasis and Vascular Calcifications**

**Emmanuel Letavernier 1,\*, Elise Bouderlique 1, Jeremy Zaworski 1, Ludovic Martin <sup>2</sup> and Michel Daudon <sup>1</sup>**


Received: 19 November 2019; Accepted: 11 December 2019; Published: 17 December 2019

**Abstract:** Pseudoxanthoma elasticum is a rare disease mainly due to *ABCC6* gene mutations and characterized by ectopic biomineralization and fragmentation of elastic fibers resulting in skin, cardiovascular and retinal calcifications. It has been recently described that pyrophosphate (a calcification inhibitor) deficiency could be the main cause of ectopic calcifications in this disease and in other genetic disorders associated to mutations of *ENPP1* or *CD73*. Patients affected by Pseudoxanthoma Elasticum seem also prone to develop kidney stones originating from papillary calcifications named Randall's plaque, and to a lesser extent may be affected by nephrocalcinosis. In this narrative review, we summarize some recent discoveries relative to the pathophysiology of this mendelian disease responsible for both cardiovascular and renal papillary calcifications, and we discuss the potential implications of pyrophosphate deficiency as a promoter of vascular calcifications in kidney stone formers and in patients affected by chronic kidney disease.

**Keywords:** pseudoxanthoma elasticum; pyrophosphate; kidney; Randall's plaque

## **1. Introduction: Pseudoxanthoma Elasticum and Related Diseases**
