title: Idiopathic calcium nephrolithiasis: a review of pathogenic mechanisms in the light of genetic studies.
abstract: BACKGROUND
  Calcium nephrolithiasis is a multifactorial disease with a polygenic milieu. Association studies identified genetic polymorphisms potentially implicated in the pathogenesis of calcium nephrolithiasis. The present article reviews the mechanisms of calcium stone formation and the potential contribution of gene polymorphisms to lithogenic mechanisms.
  
  
  CONCLUSIONS
  Endoscopy observations suggested that precipitation of calcium-oxalate on the Randall's plaque at the papilla surface may cause idiopathic calcium-oxalate stones. The Randall's plaque is a hydroxyapatite deposit in the interstitium of the kidney medulla, which resembles a soft tissue calcification. Conversely, calcium-phosphate stones may develop from crystalline deposits located at the tip of the Bellini duct. Polymorphisms of eleven genes have been associated with stones in genome-wide association studies and replicated candidate-gene association studies: VDR, SLC34A1, SLC34A4, CLDN14, and CaSR genes coding for proteins regulating tubular phosphate and calcium reabsorption; CaSR, MGP, OPN, PLAU, and UMOD genes coding for proteins preventing calcium salt precipitation; AQP1 gene coding for a water channel in the proximal tubule. The renal activity of the last gene, DGKH, is unknown. Polymorphisms in these genes may predispose to calcium-oxalate and -phosphate stones by increasing the risk of calcium-phosphate precipitation in the tubular fluid. Key Messages: Genetic findings suggest that tubular fluid supersaturation with respect to calcium and phosphate predisposes to calcium-oxalate stones by triggering cellular mechanisms that lead to the Randall's plaque formation.
authors.affiliation: Nephrology and Dialysis Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Teresa
authors.initials: T
authors.lastname: Arcidiacono
authors.forename: Alessandra
authors.initials: A
authors.lastname: Mingione
authors.forename: Lorenza
authors.initials: L
authors.lastname: Macrina
authors.forename: Francesca
authors.initials: F
authors.lastname: Pivari
authors.forename: Laura
authors.initials: L
authors.lastname: Soldati
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Vezzoli
mesh_terms: D051398:Aquaporin 1 / Q000235:genetics; D002129:Calcium Oxalate / Q000378:metabolism*; D002130:Calcium Phosphates / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000235:genetics; D057167:Claudins / Q000235:genetics; D019852:Diacylglycerol Kinase / Q000235:genetics; D016326:Extracellular Matrix Proteins / Q000235:genetics; D055106:Genome-Wide Association Study; D006801:Humans; D053040:Nephrolithiasis / Q000235:genetics* / Q000378:metabolism*; D053495:Osteopontin / Q000235:genetics; D020641:Polymorphism, Single Nucleotide; D018167:Receptors, Calcitriol / Q000235:genetics; D044169:Receptors, Calcium-Sensing / Q000235:genetics; D050613:Sodium-Phosphate Cotransporter Proteins, Type IIa / Q000235:genetics; D050615:Sodium-Phosphate Cotransporter Proteins, Type IIc / Q000235:genetics; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics; D058949:Uromodulin / Q000235:genetics; D000097568:Matrix Gla Protein
chemical_list: D051398:Aquaporin 1; D002129:Calcium Oxalate; D002130:Calcium Phosphates; D002135:Calcium-Binding Proteins; D057167:Claudins; D019852:Diacylglycerol Kinase; D016326:Extracellular Matrix Proteins; D053495:Osteopontin; D018167:Receptors, Calcitriol; D044169:Receptors, Calcium-Sensing; D050613:Sodium-Phosphate Cotransporter Proteins, Type IIa; D050615:Sodium-Phosphate Cotransporter Proteins, Type IIc; D014568:Urokinase-Type Plasminogen Activator; D058949:Uromodulin; D000097568:Matrix Gla Protein; C496020:AQP1 protein, human; C095550:CASR protein, human; C493554:SLC34A1 protein, human; C493562:SLC34A3 protein, human; C548612:UMOD protein, human; C579457:VDR protein, human; C020243:calcium phosphate; C422064:claudin 14