A novel FGF23 mutation in hyperphosphatemic familial tumoral calcinosis and its deleterious effect on protein O-glycosylation.

Background: Hyperphosphatemic familial tumoral calcinosis (HFTC) is a rare disease characterized by hyperphosphatemia and ectopic calcification, predominantly at periarticular locations. This study was performed to characterize the clinical profile of tumoral calcinosis and to identify gene mutations associated with HFTC and elucidated its pathogenic role. Methods: The three subjects (two male and one female) were aged 30, 25 and 15 years, respectively. The clinical features, histopathological findings, and outcomes of three subjects with HFTC were retrospectively reviewed. The three subjects were analyzed for FGF23, GALNT3 and KL mutations. Function of mutant gene was analyzed by western blotting and wheat germ agglutinin affinity chromatography. Results: All subjects had hyperphosphatemia and elevated calcium-phosphorus product. Calcinosis positions included the left shoulder, left index finger, and right hip. Bone and joint damage were present in two cases and multiple foci influenced body growth in one case. The histopathological features were firm, rubbery masses comprising multiple nodules of calcified material bordered by the proliferation of mononuclear or multinuclear macrophages, osteoclastic-like giant cells, fibroblasts, and chronic inflammatory cells. The novel mutation c.484A>G (p.N162D) in exon 3 of FGF23 was identified in one subject and his family members. Measurement of circulating FGF23 in the subject confirmed low intact FGF23 and increased C-terminal fragment. In vitro experiments showed that the mutant FGF23 proteins had defective O-glycosylation and impaired protein proteolysis protection. Conclusion: We identified a novel FGF23 missense mutation, and confirmed its damaging role in FGF23 protein O-glycosylation. Our findings expand the current spectrum of FGF23 variations that influence phosphorus metabolism.

Primary familial brain calcification with mild phenotype due to a new PDGFB mutation.

INTRODUCTION: Primary familial brain calcification (PFBC) is a rare neurodegenerative disorder that presents cognitive and movement impairment. To diagnose PFBC, both brain calcium accumulations visible at computed tomography (CT) and autosomal dominant or recessive inherited genetic mutation(s) in one of the known genes have to be detected. We describe the case of a female patient aging 62, who presents marked calcifications at brain CT, not due to vitamin D deficiency. These data generated the suspect of PFBC. The patient has two young sons. MATERIALS AND METHODS: The patient first, and her two sons later, underwent clinical and neurological examinations, brain CT, and blood draw for genetic analysis at our clinic. RESULTS: Patient's neurological exams detected gait impairment and tremor of the hands. Brain CT showed calcification of the basal ganglia, cerebellar dentate nuclei, and white matter. Laboratory exams identified high serum parathormone (PTH) and low plasmatic levels of vitamin D; supplementation with vitamin D normalized PTH values. Genetic analysis of the known PFBC-causing genes uncovered a new pathogenic mutation in PDGFB. The same calcifications and genetic variant were found in her younger son. DISCUSSION: Our report presents the case of a patient mildly affected by PFBC due to a novel PDGFB mutation that could have been mistaken with hyperparathyroidism if any further investigations had not been performed. Her younger asymptomatic son bore the same calcification and mutation of the mother, highlighting the importance of family pedigree collection and early diagnosis for prevention of symptoms' onset with future treatments.

Use of Teriparatide in Hyperphosphatemic Familial Tumor Calcinosis: Evaluating the Interaction Between FGF23 and PTH on the Phosphaturic Effect.

Hyperphosphatemic familial tumor calcinosis (HFTC) is a rare disease characterized by hyperphosphatemia and calcium and phosphorus crystal deposition. It occurs due to the loss of function of FGF23. Herein, we report a case of a 50-year-old woman diagnosed with HFTC (homozygous variant in the GALNT3 gene, c.803_804 C insertion) with a history of ectopic calcifications in the past 30 years. Laboratory tests on admission were as follows: phosphate (P) 7.1 mg/dL (Normal range (NR) 2.5-4.5 mg/dL), FGF23 c-terminal 2050 RU/mL (NR < 150 RU/mL), and intact FGF23 (iFGF23) 18.93 pg/mL (NR 12.0-69.0 pg/mL). Treatment with acetazolamide, sevelamer, and a phosphorus-restricted diet was started, but phosphatemia remained high and calcifications continued to progress. In an attempt to further decrease P, a 36-day cycle of teriparatide (TPTD) 20 mcg twice daily was added, decreasing P from 6.2 to 5.2 mg/dL and increasing the 1.25(OH)2 vitamin D by 34.2%. As urinalysis was not feasible at the end of the 36-day cycle, a second cycle was performed for another 28 days, producing a similar decrease in P (from 6.4 to 5.5 mg/mL) and an evident decrease in the rate of tubular reabsorption of P (from 97.2 to 85.3%), however, accompanied by a worrying increase in calciuria. The use of TPTD 20 mcg twice daily in a patient with genetic resistance to FGF23 (HFTC) was associated with consistent increase in phosphaturia and reduction in phosphatemia, in addition to an increase in calcitriol. The resulting hypercalciuria precludes the therapeutic use of TPTD in HFTC and suggests an important role of FGF23, not only in phosphate homeostasis but also in avoiding any excess of calcitriol.

Basic fibroblast growth factor inhibits aortic valvular interstitial cells calcification via Notch1 pathway.

Calcific aortic valve disease (CAVD) is an active pathological process mediated by abnormal activation and transdifferentiation of valvular interstitial cells (VICs). The present study aims to investigate the function and underlying mechanism of the basic fibroblast growth factor (BFGF) on osteogenic differentiation of VICs. Porcine VICs cultured with osteogenic induction medium are supplemented with or without BFGF. Morphology of VICs is identified by fluorescein isothiocyanate-labeled phalloidin, the cell viability is assessed by the cell counting kit-8 method, and protein and mRNA expression level of osteogenic differentiation markers, including Runx2, osteopontin, and Sp7, are verified by western blot analysis and quantitative real-time PCR, respectively. RNA sequencing is used to identify changes in gene profiles. Alizarin Red S staining is used to measure calcium deposition. The results demonstrate that the content of calcium deposition and the expression level of osteogenic markers are downregulated by supplementing BFGF. Notch1 signaling pathway is extracted as a candidate target after bioinformatics analysis by RNA sequencing. The transfection of si-Notch1 abolishes the calcification inhibitory effect of BFGF. Taken together, our findings shed the light on the mechanism and potential therapeutics of BFGF for CAVD.

Network-based screen in iPSC-derived cells reveals therapeutic candidate for heart valve disease.

Mapping the gene-regulatory networks dysregulated in human disease would allow the design of network-correcting therapies that treat the core disease mechanism. However, small molecules are traditionally screened for their effects on one to several outputs at most, biasing discovery and limiting the likelihood of true disease-modifying drug candidates. Here, we developed a machine-learning approach to identify small molecules that broadly correct gene networks dysregulated in a human induced pluripotent stem cell (iPSC) disease model of a common form of heart disease involving the aortic valve (AV). Gene network correction by the most efficacious therapeutic candidate, XCT790, generalized to patient-derived primary AV cells and was sufficient to prevent and treat AV disease in vivo in a mouse model. This strategy, made feasible by human iPSC technology, network analysis, and machine learning, may represent an effective path for drug discovery.

Microvasculopathy and soft tissue calcification in mice are governed by fetuin-A, magnesium and pyrophosphate.

Calcifications can disrupt organ function in the cardiovascular system and the kidney, and are particularly common in patients with chronic kidney disease (CKD). Fetuin-A deficient mice maintained against the genetic background DBA/2 exhibit particularly severe soft tissue calcifications, while fetuin-A deficient C57BL/6 mice remain healthy. We employed molecular genetic analysis to identify risk factors of calcification in fetuin-A deficient mice. We sought to identify pharmaceutical therapeutic targets that could be influenced by dietary of parenteral supplementation. We studied the progeny of an intercross of fetuin-A deficient DBA/2 and C57BL/6 mice to identify candidate risk genes involved in calcification. We determined that a hypomorphic mutation of the Abcc6 gene, a liver ATP transporter supplying systemic pyrophosphate, and failure to regulate the Trpm6 magnesium transporter in kidney were associated with severity of calcification. Calcification prone fetuin-A deficient mice were alternatively treated with parenteral administration of fetuin-A dietary magnesium supplementation, phosphate restriction, or by or parenteral pyrophosphate. All treatments markedly reduced soft tissue calcification, demonstrated by computed tomography, histology and tissue calcium measurement. We show that pathological ectopic calcification in fetuin-A deficient DBA/2 mice is caused by a compound deficiency of three major extracellular and systemic inhibitors of calcification, namely fetuin-A, magnesium, and pyrophosphate. All three of these are individually known to contribute to stabilize protein-mineral complexes and thus inhibit mineral precipitation from extracellular fluid. We show for the first time a compound triple deficiency that can be treated by simple dietary or parenteral supplementation. This is of special importance in patients with advanced CKD, who commonly exhibit reduced serum fetuin-A, magnesium and pyrophosphate levels.

Regulation of calcific vascular and valvular disease by nuclear receptors.

PURPOSE OF REVIEW: This review addresses recent developments in studies of lipid regulation of calcific disease of arteries and cardiac valves, including the role of nuclear receptors. The role of lipid-soluble signals and their receptors is timely given the recent evidence and concerns that lipid-lowering treatment may increase the rate of progression of coronary artery calcification, which has been long associated with increased cardiovascular risk. Understanding the mechanisms will be important for interpreting such clinical information. RECENT FINDINGS: New findings support regulation of calcific vascular and valvular disease by nuclear receptors, including the vitamin D receptor, glucocorticoid receptor, nutrient-sensing nuclear receptors (liver X receptor, farnesoid X receptor, and peroxisome proliferator-activated receptors), and sex hormone (estrogen and androgen) receptors. There were two major unexpected findings: first, vitamin D supplementation, which was previously believed to prevent or reduce vascular calcification, showed no cardiovascular benefit in large randomized, controlled trials. Second, both epidemiological studies and coronary intravascular ultrasound studies suggest that treatment with HMG-CoA reductase inhibitors increases progression of coronary artery calcification, raising a question of whether there are mechanically stable and unstable forms of coronary calcification. SUMMARY: For clinical practice and research, these new findings offer new fundamental mechanisms for vascular calcification and provide new cautionary insights for therapeutic avenues.

Nobiletin exhibits potent inhibition on tumor necrosis factor alpha-induced calcification of human aortic valve interstitial cells via targeting ABCG2 and AKR1B1.

Inflammation is considered to be one of the initial critical factors in the occurrence of calcific heart valve disease. This study was to prove Nobiletin (NBT) inhibits inflammation-caused calcification of human valve interstitial cells (hVICs) and to elucidate the involved molecular mechanisms. Tumor necrosis factor-alpha (TNF-α)-induced hVICs were treated with or without NBT. Cell growth and calcification of hVICs were assessed. RNA sequencing was utilized to investigate the gene expression changes. Molecular target prediction and docking assay were further performed. NBT interfered with hVIC growth under TNF-α condition in a dose-dependent manner also presented a gradual decrease of positive Alizarin Red S staining, down-regulation of BMP2, and RUNX2 gene expression. Based on the global gene expression cluster, control and TNF-α plus NBT group showed a high similarity versus TNF-α only group. After Venn interaction of differential expression genes (DEGs), 2,236 common DEGs were identified to display different biological functions and signaling pathways. ABCG2 and AKR1B1 were further selected as prediction targets of NBT involved in RELA, TNF, BMP2, RUNX2, etc. interactions in mediating hVIC calcification. The results show that NBT is a natural product to prevent the occurrence of heart valve calcification.

Cerebral folate deficiency in adults: A heterogeneous potentially treatable condition.

OBJECTIVE: To describe the phenotype and the response to folinic acid supplementation of cerebral folate deficiency (CFD) in adults, a disorder diagnosed on low 5-methyltetrahydro-folate (5MTHF) in cerebrospinal fluid (CSF), which can correspond to a inherited disorder of folate metabolism (IDFM) or to a metabolic consequence of various neurological diseases. METHODS: We conducted a retrospective study on 224 adult patients with neurological symptoms who had a 5MTHF CSF dosage, collecting their neurologic and neuroimaging data. RESULTS: 69 patients had CFD (CSF 5MTHF level < 41 nmol/L), 25 of them had severe CFD (sCFD; ≤25 nmol/L) with adult onset neurological symptoms in 41%. 56% of sCFD patients had an underlying identified neurologic disorder, mainly mitochondrial diseases, hepatic encephalopathy and primary brain calcifications (no identified IDFM), the others were classified as undiagnosed. sCFD patients presented most frequently pyramidal syndrome (75%), movement disorders (56%), cerebellar syndrome (50%) and intellectual disability (46%). MRI findings mostly showed white matter abnormalities (WMA; 32%) and calcifications (12%), and were normal in 23%. The clinico-radiological phenotype of sCFD patients was not clearly different from non CFD patients in terms of manifestations frequency. However, their neurological picture was more complex with a higher number of combined neurological symptoms (4.7±1.6 vs 3.4±1.7, p = .01). In Magnetic Resonance Spectroscopy (MRS), Choline/Creatine (Cho/Cr) ratio was lower in sCFD patients (n = 7) compared to non-CFD patients (n = 73) (p = .005), with good sensitivity (71%) and excellent specificity (92%). Among twenty-one CFD patients treated with folinic acid, nine had a sustained improvement, all with sCFD but one (50% of sCFD patients improved). In two undiagnosed patients with extremely low 5MTHF CSF values, MRI WMA and low Cho/Cr ratios, folinic acid treatment leaded to a dramatic clinical and radiological improvement. CONCLUSION: CSF 5MTHF dosage should be considered in patients with mitochondrial diseases, primary brain calcifications and unexplained complex neurological disorders especially if associated with WMA, since folinic acid supplementation in patients with sCFD is frequently efficient.

Warfarin, but not rivaroxaban, promotes the calcification of the aortic valve in ApoE-/- mice.

INTRODUCTION: Vitamin K antagonists, such as warfarin, are known to promote arterial calcification through blockade of gamma-carboxylation of Matrix-Gla-Protein. It is currently unknown whether other oral anticoagulants such as direct inhibitors of Factor Xa can have protective effects on the progression of aortic valve calcification. AIMS: To compare the effect of warfarin and rivaroxaban on the progression of aortic valve calcification in atherosclerotic mice. RESULTS: 42 ApoE-/- mice fed with Western-type Diet (WTD) were randomized to treatment with warfarin (n = 14), rivaroxaban (n = 14) or control (n = 14) for 8 weeks. Histological analyses were performed to quantify the calcification of aortic valve leaflets and the development of atherosclerosis. The analyses showed a significant increase in valve calcification in mice treated with warfarin as compared to WTD alone (P = .025) or rivaroxaban (P = .005), whereas no significant differences were found between rivaroxaban and WTD (P = .35). Quantification of atherosclerosis and intimal calcification was performed on the innominate artery of the mice and no differences were found between the 3 treatments as far as atherogenesis and calcium deposition is concerned. In vitro experiments performed using bovine interstitial valve cells (VIC) showed that treatment with rivaroxaban did not prevent the osteogenic conversion of the cells but reduce the over-expression of COX-2 induced by inflammatory mediators. CONCLUSION: We showed that warfarin, but not rivaroxaban, could induce calcific valve degeneration in a mouse model of atherosclerosis. Both the treatments did not significantly affect the progression of atherosclerosis. Overall, these data suggest a safer profile of rivaroxaban on the risk of cardiovascular disease progression.

Inorganic phosphorus (Pi) in CSF is a biomarker for SLC20A2-associated idiopathic basal ganglia calcification (IBGC1).

INTRODUCTION: Idiopathic basal ganglia calcification (IBGC), also called Fahr's disease or recently primary familial brain calcification (PFBC), is characterized by abnormal deposits of minerals including calcium mainly and phosphate in the brain. Mutations in SLC20A2 (IBGC1 (merged with former IBGC2 and IBGC3)), which encodes PiT-2, a phosphate transporter, is the major cause of IBGC. Recently, Slc20a2-KO mice have been showed to have elevated levels of inorganic phosphorus (Pi) in cerebrospinal fluid (CSF); however, CSF Pi levels in patients with IBGC have not been fully examined. METHODS: We investigated the cases of 29 patients with IBGC including six patients with SLC20A2 mutation and three patients with PDGFB mutation, and 13 controls. The levels of sodium (Na), potassium (K), chloride (Cl), calcium (Ca), and Pi in sera and CSF were determined by potentiometry and colorimetry. Moreover, clinical manifestations were investigated in the IBGC patients with high Pi levels in CSF. RESULTS: The study revealed that the average level of Pi in the CSF of the total group of patients with IBGC is significantly higher than that of the control group, and the levels of Pi in CSF of the IBGC patients with SLC20A2 mutations are significantly higher than those of the IBGC patients with PDGFB mutations, the other IBGC patients and controls. CONCLUSION: Results of this study suggest that the levels of CSF Pi will be a good biomarker for IBGC1.

Calcitriol Reverses the Down-Regulation Pattern of Tuberous Sclerosis Complex Genes in an In Vitro Calcification Model.

Tuberous sclerosis complex (TSC) is a neurocutaneous syndrome with autosomal dominant inheritance, and most of the cases are related to loss of function of the TSC1 and TSC2 genes. TSC may occur with a wide range of clinical findings and skin, kidney, brain, and heart are the most commonly affected organs. Brain calcifications in TSC are also described and reported as diffuse and without pattern of symmetry or bilaterality. Recently, a new discovery opened the possibility of using vitamin D (VitD) for treating cerebral calcifications. Calcitriol, the active form of VitD, was able to reduce the calcification in an in vitro model, increasing expression of a gene related to primary familial brain calcification. We show that in the same experimental model, calcitriol was also able to restore and even increase expression of genes related to TSC. This article discusses the use of calcitriol supplementation in patients with TSC, which can be a very interesting strategy due to its low cost and because it is already used in various therapies.

Targeted Pth4-expressing cell ablation impairs skeletal mineralization in zebrafish.

Skeletal development and mineralization are essential processes driven by the coordinated action of neural signals, circulating molecules and local factors. Our previous studies revealed that the novel neuropeptide Pth4, synthesized by hypothalamic cells, was involved in bone metabolism via phosphate regulation in adult zebrafish. Here, we investigate the role of pth4 during skeletal development using single-cell resolution, two-photon laser ablation of Pth4:eGFP-expressing cells and confocal imaging in vivo. Using a stable transgenic Pth4:eGFP zebrafish line, we identify Pth4:eGFP-expressing cells as post-mitotic neurons. After targeted ablation of eGFP-expressing cells in the hypothalamus, the experimental larvae exhibited impaired mineralization of the craniofacial bones whereas cartilage development was normal. In addition to a decrease in pth4 transcript levels, we noted altered expression of phex and entpd5, genes associated with phosphate homeostasis and mineralization, as well as a delay in the expression of osteoblast differentiation markers such as sp7 and sparc. Taken together, these results suggest that Pth4-expressing hypothalamic neurons participate in the regulation of bone metabolism, possibly through regulating phosphate balance during zebrafish development.

Eicosapentaenoic acid prevents arterial calcification in klotho mutant mice.

BACKGROUND: The klotho gene was identified as an "aging-suppressor" gene that accelerates arterial calcification when disrupted. Serum and vascular klotho levels are reduced in patients with chronic kidney disease, and the reduced levels are associated with arterial calcification. Intake of eicosapentaenoic acid (EPA), an n-3 fatty acid, reduces the risk of fatal coronary artery disease. However, the effects of EPA on arterial calcification have not been fully elucidated. The aim of this study was to determine the effect of EPA on arterial calcification in klotho mutant mice. METHODS AND RESULTS: Four-week-old klotho mutant mice and wild-type (WT) mice were given a diet containing 5% EPA (EPA food, klotho and WT: n = 12, each) or not containing EPA (control food, klotho and WT: n = 12, each) for 4 weeks. Calcium volume scores of thoracic and abdominal aortas assessed by computed tomography were significantly elevated in klotho mice after 4 weeks of control food, but they were not elevated in klotho mice after EPA food or in WT mice. Serum levels of EPA and resolvin E1, an active metabolite of EPA, in EPA food-fed mice were significantly increased compared to those in control food-fed mice. An oxidative stress PCR array followed by quantitative PCR revealed that NADPH oxidase-4 (NOX4), an enzyme that generates superoxide, gene expression was up-regulated in arterial smooth muscle cells (SMCs) of klotho mice. Activity of NOX was also significantly higher in SMCs of klotho mice than in those of WT mice. EPA decreased expression levels of the NOX4 gene and NOX activity. GPR120, a receptor of n-3 fatty acids, gene knockdown by siRNA canceled effects of EPA on NOX4 gene expression and NOX activity in arterial SMCs of klotho mice. CONCLUSIONS: EPA prevents arterial calcification together with reduction of NOX gene expression and activity via GPR120 in klotho mutant mice.

Symmetrical thalamic calcification: A trio whole exome sequencing negative series.

Symmetrical thalamic calcification or bilateral symmetrical thalamic gliosis presents at delivery with hypertonia, fixed flexion contractures and prominent bulbar signs, without preceding perinatal asphyxia. At post-mortem, there is evidence of bilateral symmetrical selective thalamic neuronal encrustation and gliosis. To date, 27 cases are published with no underlying diagnosis identified. Two affected children from singleton pregnancies were reported and therefore, a genetic cause proposed. No previous reports have performed genetic testing to confirm or reject this hypothesis. We report three additional cases of this rare condition, expanding the clinical and pathological phenotype. We performed trio whole exome sequencing, the first in this cohort of patients, and did not identify a pathogenic variant. As postulated in the original report, the likely underlying mechanism is antenatal hypoxia in the third trimester.

Pulmonary Alveolar Microlithiasis.

Pulmonary alveolar microlithiasis (PAM) is a genetic lung disorder that is characterized by the accumulation of calcium phosphate deposits in the alveolar spaces of the lung. Mutations in the type II sodium phosphate cotransporter, NPT2b, have been reported in patients with PAM. PAM progresses gradually, often producing incremental dyspnea on exertion, desaturation in young adulthood, and respiratory insufficiency by late middle age. Treatment remains supportive, including supplemental oxygen therapy. For patients with end-stage disease, lung transplantation is available as a last resort. The recent development of a laboratory animal model has revealed several promising treatment approaches for future trials.

Pharmacological Regulation of In Situ Tissue Stem Cells Differentiation for Soft Tissue Calcification Treatment.

Calcification of soft tissues, such as heart valves and tendons, is a common clinical problem with limited therapeutics. Tissue specific stem/progenitor cells proliferate to repopulate injured tissues. But some of them become divergent to the direction of ossification in the local pathological microenvironment, thereby representing a cellular target for pharmacological approach. We observed that HIF-2alpha (encoded by EPAS1 inclined form) signaling is markedly activated within stem/progenitor cells recruited at calcified sites of diseased human tendons and heart valves. Proinflammatory microenvironment, rather than hypoxia, is correlated with HIF-2alpha activation and promoted osteochondrogenic differentiation of tendon stem/progenitor cells (TSPCs). Abnormal upregulation of HIF-2alpha served as a key switch to direct TSPCs differentiation into osteochondral-lineage rather than teno-lineage. Notably, Scleraxis (Scx), an essential tendon specific transcription factor, was suppressed on constitutive activation of HIF-2alpha and mediated the effect of HIF-2alpha on TSPCs fate decision. Moreover, pharmacological inhibition of HIF-2alpha with digoxin, which is a widely utilized drug, can efficiently inhibit calcification and enhance tenogenesis in vitro and in the Achilles's tendinopathy model. Taken together, these findings reveal the significant role of the tissue stem/progenitor cells fate decision and suggest that pharmacological regulation of HIF-2alpha function is a promising approach for soft tissue calcification treatment.

Nicotinamide treatment in a murine model of familial tumoral calcinosis reduces serum Fgf23 and raises heart calcium.

Mutations in the GALNT3 gene result in familial tumoral calcinosis, characterized by persistent hyperphosphatemia and ectopic calcific masses in soft tissues. Since calcific masses often recur after surgical removal, a more permanent solution to the problem is required. Nicotinamide is reported to lower serum phosphate by decreasing sodium-dependent phosphate co-transporters in the gut and kidney. However, its effectiveness in tumoral calcinosis remains unknown. In this study, we investigated nicotinamide as a potential therapy for tumoral calcinosis, using a murine model of the disease-Galnt3 knockout mice. Initially, five different doses of nicotinamide were given to normal heterozygous mice intraperitoneally or orally. Treatment had no effect on serum phosphate levels, but serum levels of a phosphaturic hormone, fibroblast growth factor 23 (Fgf23), decreased in a dose-dependent manner. Subsequently, high-dose nicotinamide (40mM) was tested in Galnt3 knockout mice fed a high phosphate diet. The radiographic data pre- and post-treatment showed that nicotinamide did not reverse the calcification. However, the treatment retarded calcification growth after 4weeks, while in the untreated animals, calcifications increased in size. The therapy did not affect serum phosphate levels, but intact Fgf23 decreased in the treated mice. The treated mice also had increased calcium in the heart. In summary, nicotinamide did not alter serum phosphate levels, likely due to compensatory decrease in Fgf23 to counteract the phosphate lowering effect of nicotinamide. Although increased calcium accumulation in the heart is a concern, the therapy appears to slow down the progression of ectopic calcifications.