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Sehgal A, Milman T, Li Q, Pulido JS. Histological Findings in the Eyes of Abcc6 Knockout Rat Model of Pseudoxanthoma Elasticum. Transl Vis Sci Technol 2024; 13:29. [PMID: 38656313 PMCID: PMC11044839 DOI: 10.1167/tvst.13.4.29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 02/07/2024] [Indexed: 04/26/2024] Open
Abstract
Purpose To describe the ocular findings of murine pseudoxanthoma elasticum (PXE) models with ATP-binding cassette subfamily C member 6 (Abcc6) gene knockout. Methods This experiment was conducted in four Abcc6-/- rats and compared with six wild-type Abcc6+/+ control rats. The animals underwent necropsy at 6 months of age. Histological examination of the eyes was performed. Results Histological examination of eight eyes from four Abcc6-/- rats revealed multiple nodular foci of calcification in the uvea, sclera, and conjunctiva, focally in perivascular distribution, as well as linear and nodular calcification of Bruch's membrane. Calcific foci were not associated with inflammation in the knockout rats. There was no evidence of calcification in control eyes. Discussion The Abcc6-/- rat model shows that PXE can affect multiple ocular tissues beyond the calcification in Bruch's membrane noted in human eyes. Nodular calcific foci probably correspond to comet lesions seen in patients with PXE. The presence of ectopic calcium without inflammation distinguishes it from inflammatory calcium deposition in atherosclerosis. Further studies are needed to determine why PXE does not cause inflammatory infiltration. Translational Relevance The Abcc6-/- murine model may be suitable for studying ocular PXE pathophysiology and ectopic calcification and developing effective therapies.
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Affiliation(s)
- Anahita Sehgal
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA, USA
| | - Tatyana Milman
- Department of Ophthalmology, Wills Eye Hospital, Sidney Kimmel Medical College of Thomas Jefferson University, Philadelphia, PA, USA
- Department of Pathology, Wills Eye Hospital, Sidney Kimmel Medical College of Thomas Jefferson University, Philadelphia, PA, USA
| | - Qiaoli Li
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA, USA
- PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA, USA
| | - Jose S. Pulido
- Department of Ophthalmology, Wills Eye Hospital, Sidney Kimmel Medical College of Thomas Jefferson University, Philadelphia, PA, USA
- Bower Laboratory for Translational Medicine Vickie and Jack Farber, Vision Research Center at Wills Eye Hospital, Wills Eye Hospital, Philadelphia, PA, USA
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2
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Kauffenstein G, Martin L, Le Saux O. The Purinergic Nature of Pseudoxanthoma Elasticum. BIOLOGY 2024; 13:74. [PMID: 38392293 PMCID: PMC10886499 DOI: 10.3390/biology13020074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/13/2024] [Accepted: 01/19/2024] [Indexed: 02/24/2024]
Abstract
Pseudoxanthoma Elasticum (PXE) is an inherited disease characterized by elastic fiber calcification in the eyes, the skin and the cardiovascular system. PXE results from mutations in ABCC6 that encodes an ABC transporter primarily expressed in the liver and kidneys. It took nearly 15 years after identifying the gene to better understand the etiology of PXE. ABCC6 function facilitates the efflux of ATP, which is sequentially hydrolyzed by the ectonucleotidases ENPP1 and CD73 into pyrophosphate (PPi) and adenosine, both inhibitors of calcification. PXE, together with General Arterial Calcification of Infancy (GACI caused by ENPP1 mutations) as well as Calcification of Joints and Arteries (CALJA caused by NT5E/CD73 mutations), forms a disease continuum with overlapping phenotypes and shares steps of the same molecular pathway. The explanation of these phenotypes place ABCC6 as an upstream regulator of a purinergic pathway (ABCC6 → ENPP1 → CD73 → TNAP) that notably inhibits mineralization by maintaining a physiological Pi/PPi ratio in connective tissues. Based on a review of the literature and our recent experimental data, we suggest that PXE (and GACI/CALJA) be considered as an authentic "purinergic disease". In this article, we recapitulate the pathobiology of PXE and review molecular and physiological data showing that, beyond PPi deficiency and ectopic calcification, PXE is associated with wide and complex alterations of purinergic systems. Finally, we speculate on the future prospects regarding purinergic signaling and other aspects of this disease.
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Affiliation(s)
- Gilles Kauffenstein
- UMR INSERM 1260, Regenerative Nanomedicine, University of Strasbourg, 67084 Strasbourg, France
| | - Ludovic Martin
- PXE Consultation Center, MAGEC Nord Reference Center for Rare Skin Diseases, Angers University Hospital, 49000 Angers, France
- MITOVASC-UMR CNRS 6015 INSERM 1083, University of Angers, 49000 Angers, France
| | - Olivier Le Saux
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96822, USA
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Yao R, Yang F, Zhang Q, Yu T, Yu Y, Chang G, Wang X. Clinical and Molecular Characterization of a Patient with Generalized Arterial Calcification of Infancy Caused by Rare ABCC6 Mutation. J Pers Med 2023; 14:54. [PMID: 38248755 PMCID: PMC10817667 DOI: 10.3390/jpm14010054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 12/19/2023] [Accepted: 12/25/2023] [Indexed: 01/23/2024] Open
Abstract
Generalized arterial calcification of infancy (GACI) is a rare autosomal-recessive disease characterized by extensive arterial calcification in infancy, with clinical manifestations such as arterial stenoses and heart failure. The ENPP1 inactivation mutation has been identified as a potential defect in most of the cases of GACI, while mutations in ABCC6 are demonstrated in patients who are genotyped as pseudoxanthoma elasticum and only limited cases of GACI are reported. Whole-exome sequencing was applied for the detection of pathogenic variants. Copy-number variants of pathogenic genes were also evaluated through a bioinformatic process and were further validated by real-time quantitative PCR. In this report, we described the clinical information and treatment of a patient with extensive arterial calcification. We have identified the underlying cause as biallelic mutations in ABCC6 (NM_00117: exon30, c.4223_4227dupAGCTC p.(Leu1410Serfs*56)) and a unique exonic deletion that spans from the first to the fourth exons of ABCC6 (chr16:16313388-16330869)). This discovery was made by utilizing a combined genetic testing approach. With the review of previously reported GACI patients with ABCC6 mutation, our work contributed to enriching the mutation spectrum of GACI and providing further information on this rare form of inherited disorder.
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Affiliation(s)
- Ruen Yao
- Department of Medical Genetics and Antenatal Diagnostic Center, Hainan Branch, Shanghai Children’s Medical Center, School of Medicine, Shanghai Jiao Tong University, Sanya 572022, China; (R.Y.)
- Department of Medical Genetics and Molecular Diagnostic Laboratory, Shanghai Children’s Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Fan Yang
- Clinical Research Ward, Shanghai Children’s Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China; (F.Y.)
| | - Qianwen Zhang
- Department of Endocrinology and Metabolism, Shanghai Children’s Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Tingting Yu
- Department of Medical Genetics and Molecular Diagnostic Laboratory, Shanghai Children’s Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Ying Yu
- Department of Medical Genetics and Antenatal Diagnostic Center, Hainan Branch, Shanghai Children’s Medical Center, School of Medicine, Shanghai Jiao Tong University, Sanya 572022, China; (R.Y.)
| | - Guoying Chang
- Clinical Research Ward, Shanghai Children’s Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China; (F.Y.)
- Department of Endocrinology and Metabolism, Shanghai Children’s Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Xiumin Wang
- Clinical Research Ward, Shanghai Children’s Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China; (F.Y.)
- Department of Endocrinology and Metabolism, Shanghai Children’s Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
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Plümers R, Lindenkamp C, Osterhage MR, Knabbe C, Hendig D. Matrix Metalloproteinases Contribute to the Calcification Phenotype in Pseudoxanthoma Elasticum. Biomolecules 2023; 13:672. [PMID: 37189419 PMCID: PMC10135689 DOI: 10.3390/biom13040672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 03/16/2023] [Accepted: 04/06/2023] [Indexed: 05/17/2023] Open
Abstract
Ectopic calcification and dysregulated extracellular matrix remodeling are prominent hallmarks of the complex heterogenous pathobiochemistry of pseudoxanthoma elasticum (PXE). The disease arises from mutations in ABCC6, an ATP-binding cassette transporter expressed predominantly in the liver. Neither its substrate nor the mechanisms by which it contributes to PXE are completely understood. The fibroblasts isolated from PXE patients and Abcc6-/- mice were subjected to RNA sequencing. A group of matrix metalloproteinases (MMPs) clustering on human chromosome 11q21-23, respectively, murine chromosome 9, was found to be overexpressed. A real-time quantitative polymerase chain reaction, enzyme-linked immunosorbent assay and immunofluorescent staining confirmed these findings. The induction of calcification by CaCl2 resulted in the elevated expression of selected MMPs. On this basis, the influence of the MMP inhibitor Marimastat (BB-2516) on calcification was assessed. PXE fibroblasts (PXEFs) exhibited a pro-calcification phenotype basally. PXEF and normal human dermal fibroblasts responded with calcium deposit accumulation and the induced expression of osteopontin to the addition of Marimastat to the calcifying medium. The raised MMP expression in PXEFs and during cultivation with calcium indicates a correlation of ECM remodeling and ectopic calcification in PXE pathobiochemistry. We assume that MMPs make elastic fibers accessible to controlled, potentially osteopontin-dependent calcium deposition under calcifying conditions.
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Affiliation(s)
| | | | | | | | - Doris Hendig
- Herz- und Diabeteszentrum Nordrhein-Westfalen, Institut für Laboratoriums- und Transfusionsmedizin, Universitätsklinik der Ruhr-Universität Bochum, Georgstraße 11, 32545 Bad Oeynhausen, Germany
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Ralph D, Levine MA, Richard G, Morrow M, Flynn E, Uitto J, Li Q. Mutation update: Variants of the ENPP1 gene in pathologic calcification, hypophosphatemic rickets, and cutaneous hypopigmentation with punctate keratoderma. Hum Mutat 2022; 43:1183-1200. [PMID: 35475527 PMCID: PMC9357117 DOI: 10.1002/humu.24391] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/07/2022] [Accepted: 04/22/2022] [Indexed: 11/11/2022]
Abstract
ENPP1 encodes ENPP1, an ectonucleotidase catalyzing hydrolysis of ATP to AMP and inorganic pyrophosphate (PPi), and an endogenous plasma protein physiologically preventing ectopic calcification of connective tissues. Mutations in ENPP1 have been reported in association with a range of human genetic diseases. In this mutation update, we provide a comprehensive review of all the pathogenic variants, likely pathogenic variants, and variants of unknown significance in ENPP1 associated with three autosomal recessive disorders-generalized arterial calcification of infancy (GACI), autosomal recessive hypophosphatemic rickets type 2 (ARHR2), and pseudoxanthoma elasticum (PXE), as well as with a predominantly autosomal dominant disorder-Cole disease. The classification of all variants is determined using the latest ACMG guidelines. A total of 140 ENPP1 variants were curated consisting of 133 previously reported variants and seven novel variants, with missense variants being the most prevalent (70.0%, 98/140). While the pathogenic variants are widely distributed in the ENPP1 gene of patientsgen without apparent genotype-phenotype correlation, eight out of nine variants associated with Cole disease are confined to the somatomedin-B-like (SMB) domains critical for homo-dimerization of the ENPP1 protein.
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Affiliation(s)
- Douglas Ralph
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA
- Genetics, Genomics and Cancer Biology Ph.D. Program, Jefferson College of Life Sciences, Thomas Jefferson University, Philadelphia, PA
- PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA
| | - Michael A. Levine
- Division of Endocrinology and Diabetes, Children’s Hospital of Philadelphia, Philadelphia, PA
| | | | | | | | - Jouni Uitto
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA
- PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA
| | - Qiaoli Li
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA
- PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA
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Ralph D, Nitschke Y, Levine MA, Caffet M, Wurst T, Saeidian AH, Youssefian L, Vahidnezhad H, Terry SF, Rutsch F, Uitto J, Li Q. ENPP1 variants in patients with GACI and PXE expand the clinical and genetic heterogeneity of heritable disorders of ectopic calcification. PLoS Genet 2022; 18:e1010192. [PMID: 35482848 PMCID: PMC9089899 DOI: 10.1371/journal.pgen.1010192] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 05/10/2022] [Accepted: 04/05/2022] [Indexed: 12/17/2022] Open
Abstract
Pseudoxanthoma elasticum (PXE) and generalized arterial calcification of infancy (GACI) are clinically distinct genetic entities of ectopic calcification associated with differentially reduced circulating levels of inorganic pyrophosphate (PPi), a potent endogenous inhibitor of calcification. Variants in ENPP1, the gene mutated in GACI, have not been associated with classic PXE. Here we report the clinical, laboratory, and molecular evaluations of ten GACI and two PXE patients from five and two unrelated families registered in GACI Global and PXE International databases, respectively. All patients were found to carry biallelic variants in ENPP1. Among ten ENPP1 variants, one homozygous variant demonstrated uniparental disomy inheritance. Functional assessment of five previously unreported ENPP1 variants suggested pathogenicity. The two PXE patients, currently 57 and 27 years of age, had diagnostic features of PXE and had not manifested the GACI phenotype. The similarly reduced PPi plasma concentrations in the PXE and GACI patients in our study correlate poorly with their disease severity. This study demonstrates that in addition to GACI, ENPP1 variants can cause classic PXE, expanding the clinical and genetic heterogeneity of heritable ectopic calcification disorders. Furthermore, the results challenge the current prevailing concept that plasma PPi is the only factor governing the severity of ectopic calcification. Biallelic inactivating mutations in the ENPP1 gene cause generalized arterial calcification of infancy (GACI), a frequently fatal disease characterized by infantile onset of widespread arterial calcification and/or narrowing of large and medium-sized vessels often resulting in the early demise of affected individuals. Significantly reduced, almost zero plasma levels of a potent and endogenous calcification inhibitor, inorganic pyrophosphate (PPi), is thought to be the underlying cause of vascular calcification in GACI. Mutations in ENPP1 have not been found in patients with pseudoxanthoma elasticum (PXE), another genetic multisystem ectopic calcification disorder caused by mutations in the ABCC6 gene. This study reports that ENPP1 mutations can also cause PXE with more favorable clinical outcomes. In addition, it was previously thought that plasma PPi levels correlate with vascular calcification severity. However, we here show that vascular calcification severity does not correlate with plasma PPi levels. The results suggest that in addition to PPi, the long-believed determinant of ectopic calcification, additional mechanisms may be at play in regulating ectopic calcification.
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Affiliation(s)
- Douglas Ralph
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, and Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- Genetics, Genomics and Cancer Biology Ph.D. Program, Jefferson College of Life Sciences, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | | | - Michael A. Levine
- Division of Endocrinology and Diabetes, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Matthew Caffet
- PXE International, Inc., Damascus, Maryland, United States of America
| | - Tamara Wurst
- PXE International, Inc., Damascus, Maryland, United States of America
| | - Amir Hossein Saeidian
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, and Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- Genetics, Genomics and Cancer Biology Ph.D. Program, Jefferson College of Life Sciences, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Leila Youssefian
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, and Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Hassan Vahidnezhad
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, and Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Sharon F. Terry
- PXE International, Inc., Damascus, Maryland, United States of America
| | - Frank Rutsch
- Münster University Children’s Hospital, Münster, Germany
| | - Jouni Uitto
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, and Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Qiaoli Li
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, and Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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7
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Li Q, Terry SF, Uitto J. Comment on "Clinical practice guidelines for pseudoxanthoma elasticum (2017)": The importance of mutation analysis. J Dermatol 2022; 49:e248-e249. [PMID: 35318717 DOI: 10.1111/1346-8138.16354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 11/30/2022]
Affiliation(s)
- Qiaoli Li
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, and Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.,PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | | | - Jouni Uitto
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, and Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.,PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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Ralph D, van de Wetering K, Uitto J, Li Q. Inorganic Pyrophosphate Deficiency Syndromes and Potential Treatments for Pathologic Tissue Calcification. THE AMERICAN JOURNAL OF PATHOLOGY 2022; 192:762-770. [PMID: 35182493 PMCID: PMC9088198 DOI: 10.1016/j.ajpath.2022.01.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/19/2022] [Accepted: 01/24/2022] [Indexed: 02/08/2023]
Abstract
Pathologic soft tissue calcification can occur in both genetic and acquired clinical conditions, causing significant morbidity and mortality. Although the pathomechanisms of pathologic calcification are poorly understood, major progress has been made in recent years in defining the underlying genetic defects in Mendelian disorders of ectopic calcification. This review presents an overview of the pathophysiology of five monogenic disorders of pathologic calcification: pseudoxanthoma elasticum, generalized arterial calcification of infancy, arterial calcification due to deficiency of CD73, ankylosis, and progeria. These hereditary disorders, caused by mutations in genes encoding ATP binding cassette subfamily C member 6, ectonucleotide pyrophosphatase/phosphodiesterase 1, CD73, progressive ankylosis protein, and lamin A/C proteins, respectively, are inorganic pyrophosphate (PPi) deficiency syndromes with reduced circulating levels of PPi, the principal physiologic inhibitor of calcium hydroxyapatite deposition in soft connective tissues. In addition to genetic diseases, PPi deficiency has been encountered in acquired clinical conditions accompanied by pathologic calcification. Because specific and effective treatments are lacking for pathologic calcification, the unifying finding of PPi deficiency suggests that PPi-targeted therapies may be beneficial to counteract pathologic soft tissue calcification in both genetic and acquired diseases.
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Affiliation(s)
- Douglas Ralph
- Genetics, Genomics, and Cancer Biology Ph.D. Program, Jefferson College of Life Sciences, Thomas Jefferson University, Philadelphia, Pennsylvania; Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, and the PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Koen van de Wetering
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, and the PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Jouni Uitto
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, and the PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Qiaoli Li
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, and the PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, Pennsylvania.
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Tiplica GS, Fritz K, Butacu AI, Ungureanu L, Sălăvăstru CM. Gutartige nichtmelanozytäre Hauttumoren bei Syndromen. Hautarzt 2022; 73:114-126. [DOI: 10.1007/s00105-022-04947-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/07/2022] [Indexed: 12/24/2022]
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10
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Saeidian AH, Youssefian L, Huang J, Touati A, Vahidnezhad H, Kowal L, Caffet M, Wurst T, Singh J, Snook AE, Ryu E, Fortina P, Terry SF, Schoenecker JG, Uitto J, Li Q. Genetic heterogeneity of heritable ectopic mineralization disorders in a large international cohort. Genet Med 2021; 24:75-86. [PMID: 34906475 DOI: 10.1016/j.gim.2021.08.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 06/17/2021] [Accepted: 08/16/2021] [Indexed: 12/25/2022] Open
Abstract
PURPOSE Heritable ectopic mineralization disorders comprise a group of conditions with a broad range of clinical manifestations in nonskeletal connective tissues. We report the genetic findings from a large international cohort of 478 patients afflicted with ectopic mineralization. METHODS Sequence variations were identified using a next-generation sequencing panel consisting of 29 genes reported in association with ectopic mineralization. The pathogenicity of select splicing and missense variants was analyzed in experimental systems in vitro and in vivo. RESULTS A total of 872 variants of unknown significance as well as likely pathogenic and pathogenic variants were disclosed in 25 genes. A total of 159 distinct variants were identified in 425 patients in ABCC6, the gene responsible for pseudoxanthoma elasticum, a heritable multisystem ectopic mineralization disorder. The interpretation of variant pathogenicity relying on bioinformatic predictions did not provide a consensus. Our in vitro and in vivo functional assessment of 14 ABCC6 variants highlighted this dilemma and provided unambiguous interpretations to their pathogenicity. CONCLUSION The results expand the ABCC6 variant repertoire, shed new light on the genetic heterogeneity of heritable ectopic mineralization disorders, and provide evidence that functional characterization in appropriate experimental systems is necessary to determine the pathogenicity of genetic variants.
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Affiliation(s)
- Amir Hossein Saeidian
- Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA; Department of Dermatology & Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA; Genetics, Genomics & Cancer Biology PhD Program, College of Life Sciences, Thomas Jefferson University, Philadelphia, PA
| | - Leila Youssefian
- Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA; Department of Dermatology & Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA
| | - Jianhe Huang
- Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA; Department of Dermatology & Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA; PXE International Center of Excellence in Research & Clinical Care, Thomas Jefferson University, Philadelphia, PA
| | - Andrew Touati
- Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA; Department of Dermatology & Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA
| | - Hassan Vahidnezhad
- Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA; Department of Dermatology & Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA
| | - Luke Kowal
- Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA
| | | | | | - Jagmohan Singh
- Department of Pharmacology & Experimental Therapeutics, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, PA
| | - Adam E Snook
- Department of Pharmacology & Experimental Therapeutics, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, PA
| | - Ellen Ryu
- Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA
| | - Paolo Fortina
- Department of Cancer Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA
| | | | - Jonathan G Schoenecker
- Department of Orthopedics and Vanderbilt Center for Bone Biology, Vanderbilt University Medical Center, Nashville, TN
| | - Jouni Uitto
- Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA; Department of Dermatology & Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA; PXE International Center of Excellence in Research & Clinical Care, Thomas Jefferson University, Philadelphia, PA
| | - Qiaoli Li
- Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA; Department of Dermatology & Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA; PXE International Center of Excellence in Research & Clinical Care, Thomas Jefferson University, Philadelphia, PA.
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11
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Kowal L, Huang J, Luo H, Singh J, Snook AE, Uitto J, Li Q. Functional Assessment of Missense Variants in the ABCC6 Gene Implicated in Pseudoxanthoma Elasticum, a Heritable Ectopic Mineralization Disorder. J Invest Dermatol 2021; 142:1085-1093. [PMID: 34597610 DOI: 10.1016/j.jid.2021.08.435] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 08/16/2021] [Accepted: 08/25/2021] [Indexed: 12/14/2022]
Abstract
Pseudoxanthoma elasticum, a heritable multisystem ectopic mineralization disorder, is caused by inactivating mutations in the ABCC6 gene. The encoded protein, ABCC6, a transmembrane transporter, has a specialized efflux function in hepatocytes by contributing to plasma levels of inorganic pyrophosphate, a potent inhibitor of mineralization in soft connective tissues. Reduced plasma inorganic pyrophosphate levels underlie the ectopic mineralization in pseudoxanthoma elasticum. In this study, we characterized the pathogenicity of three human ABCC6 missense variants using an adenovirus-mediated liver-specific ABCC6 transgene expression system in an Abcc6-/- mouse model of pseudoxanthoma elasticum. Variants p.L420V and p.R1064W were found benign because they had abundance and plasma membrane localization in hepatocytes similar to the wild-type human ABCC6 transgene, normalized plasma inorganic pyrophosphate levels, and prevented mineralization in the dermal sheath of vibrissae in muzzle skin, a phenotypic hallmark in the Abcc6-/- mice. In contrast, p.S400F was shown to be pathogenic because it failed to normalize plasma inorganic pyrophosphate levels and had no effect on ectopic mineralization despite its normal expression and proper localization in hepatocytes. These results showed that adenovirus-mediated hepatic ABCC6 expression in Abcc6-/- mice can provide a model system to effectively elucidate the multifaceted functional consequences of human ABCC6 missense variants identified in patients with pseudoxanthoma elasticum.
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Affiliation(s)
- Luke Kowal
- PXE International Center of Excellence in Research and Clinical Care, Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Jianhe Huang
- PXE International Center of Excellence in Research and Clinical Care, Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Hongbin Luo
- PXE International Center of Excellence in Research and Clinical Care, Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, USA; Department of Dermatology, The First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China
| | - Jagmohan Singh
- Department of Pharmacology and Experimental Therapeutics, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Adam E Snook
- Department of Pharmacology and Experimental Therapeutics, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Jouni Uitto
- PXE International Center of Excellence in Research and Clinical Care, Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Qiaoli Li
- PXE International Center of Excellence in Research and Clinical Care, Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
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12
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Lofaro FD, Mucciolo DP, Murro V, Pavese L, Quaglino D, Boraldi F. A Case Report of Pseudoxanthoma Elasticum with Rare Sequence Variants in Genes Related to Inherited Retinal Diseases. Diagnostics (Basel) 2021; 11:diagnostics11101800. [PMID: 34679498 PMCID: PMC8534466 DOI: 10.3390/diagnostics11101800] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/17/2021] [Accepted: 09/27/2021] [Indexed: 01/11/2023] Open
Abstract
A case of a patient with an early and severe visual impairment is described. Due to the occurrence of skin papules a suspect of pseudoxanthoma elasticum (PXE) was posed. PXE is a rare autosomal recessive disease clinically characterized by skin, cardiovascular and ocular manifestations, these last being those that most severely affect patients’ quality of life. A whole exome sequencing approach focusing on 340 genes related to the calcification process and/or to inherited retinal diseases (IRDs) was performed. Rare monoallelic sequence variants in ABCA4, ABCC6, IMPG1, POC1B and RAX2 were found. The presence of calcified elastic fibers was assessed by ultrastructural analysis on a skin biopsy. Diagnosis of PXE was based on clinical, biomolecular and morphological results, although the additional involvement of several IRD genes is important to explain the unexpectedly severe ophthalmological phenotype of the patient also in prognostic and therapeutic perspectives. Data indicate that genetic screening using a wide-spectrum analysis approach is essential to assist ophthalmologists in improving patient counseling.
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Affiliation(s)
- Francesco Demetrio Lofaro
- Department of Life Science, University of Modena and Reggio Emilia, 41125 Modena, Italy; (F.D.L.); (D.Q.)
| | - Dario Pasquale Mucciolo
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Eye Clinic, 50139 Florence, Italy; (D.P.M.); (V.M.); (L.P.)
| | - Vittoria Murro
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Eye Clinic, 50139 Florence, Italy; (D.P.M.); (V.M.); (L.P.)
| | - Laura Pavese
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Eye Clinic, 50139 Florence, Italy; (D.P.M.); (V.M.); (L.P.)
| | - Daniela Quaglino
- Department of Life Science, University of Modena and Reggio Emilia, 41125 Modena, Italy; (F.D.L.); (D.Q.)
| | - Federica Boraldi
- Department of Life Science, University of Modena and Reggio Emilia, 41125 Modena, Italy; (F.D.L.); (D.Q.)
- Correspondence:
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13
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Lofaro FD, Mucciolo DP, Murro V, Pavese L, Quaglino D, Boraldi F. From Clinical Diagnosis to the Discovery of Multigene Rare Sequence Variants in Pseudoxanthoma elasticum: A Case Report. Front Med (Lausanne) 2021; 8:726856. [PMID: 34513887 PMCID: PMC8427021 DOI: 10.3389/fmed.2021.726856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 07/30/2021] [Indexed: 12/03/2022] Open
Abstract
Pseudoxanthoma elasticum (PXE) is a rare autosomal recessive disease clinically characterised by early cutaneous alterations, and by late clinically relevant ocular, and cardiovascular manifestations. ABCC6 genetic tests are used to confirm clinical PXE diagnosis, but this strategy may be rather challenging when only one ABCC6 pathogenic variant is found. A next-generation sequencing approach focusing on 362 genes related to the calcification process and/or to inherited retinal diseases was performed on a patient with clinical PXE diagnosis (skin papules and laxity, angioid streaks, and atrophy) who was carrier of only one ABCC6 rare sequence variant. Beside ABCC6, several rare sequence variants were detected which can contribute either to the occurrence of calcification (GGCX and SERPINF1 genes) and/or to ophthalmological manifestations (ABCA4, AGBL5, CLUAP1, and KCNV2 genes). This wide-spectrum analysis approach facilitates the identification of rare variants possibly involved in PXE, thus avoiding invasive skin biopsy as well as expensive and time-consuming diagnostic odyssey and allows to broaden and to deepen the knowledge on this complex rare disease and to improve patients' counselling, also with a future perspective of personalised medicine.
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Affiliation(s)
| | - Dario Pasquale Mucciolo
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Eye Clinic, Florence, Italy
| | - Vittoria Murro
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Eye Clinic, Florence, Italy
| | - Laura Pavese
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Eye Clinic, Florence, Italy
| | - Daniela Quaglino
- Department of Life Science, University of Modena and Reggio Emilia, Modena, Italy
| | - Federica Boraldi
- Department of Life Science, University of Modena and Reggio Emilia, Modena, Italy
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14
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Shimada BK, Pomozi V, Zoll J, Kuo S, Martin L, Le Saux O. ABCC6, Pyrophosphate and Ectopic Calcification: Therapeutic Solutions. Int J Mol Sci 2021; 22:ijms22094555. [PMID: 33925341 PMCID: PMC8123679 DOI: 10.3390/ijms22094555] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/20/2021] [Accepted: 04/21/2021] [Indexed: 12/11/2022] Open
Abstract
Pathological (ectopic) mineralization of soft tissues occurs during aging, in several common conditions such as diabetes, hypercholesterolemia, and renal failure and in certain genetic disorders. Pseudoxanthoma elasticum (PXE), a multi-organ disease affecting dermal, ocular, and cardiovascular tissues, is a model for ectopic mineralization disorders. ABCC6 dysfunction is the primary cause of PXE, but also some cases of generalized arterial calcification of infancy (GACI). ABCC6 deficiency in mice underlies an inducible dystrophic cardiac calcification phenotype (DCC). These calcification diseases are part of a spectrum of mineralization disorders that also includes Calcification of Joints and Arteries (CALJA). Since the identification of ABCC6 as the “PXE gene” and the development of several animal models (mice, rat, and zebrafish), there has been significant progress in our understanding of the molecular genetics, the clinical phenotypes, and pathogenesis of these diseases, which share similarities with more common conditions with abnormal calcification. ABCC6 facilitates the cellular efflux of ATP, which is rapidly converted into inorganic pyrophosphate (PPi) and adenosine by the ectonucleotidases NPP1 and CD73 (NT5E). PPi is a potent endogenous inhibitor of calcification, whereas adenosine indirectly contributes to calcification inhibition by suppressing the synthesis of tissue non-specific alkaline phosphatase (TNAP). At present, therapies only exist to alleviate symptoms for both PXE and GACI; however, extensive studies have resulted in several novel approaches to treating PXE and GACI. This review seeks to summarize the role of ABCC6 in ectopic calcification in PXE and other calcification disorders, and discuss therapeutic strategies targeting various proteins in the pathway (ABCC6, NPP1, and TNAP) and direct inhibition of calcification via supplementation by various compounds.
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Affiliation(s)
- Briana K Shimada
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96817, USA
| | - Viola Pomozi
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, 1117 Budapest, Hungary
| | - Janna Zoll
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96817, USA
| | - Sheree Kuo
- Department of Pediatrics, Kapi'olani Medical Center for Women and Children, University of Hawaii, Honolulu, HI 96826, USA
| | - Ludovic Martin
- PXE Consultation Center, MAGEC Reference Center for Rare Skin Diseases, Angers University Hospital, 49100 Angers, France
- BNMI, CNRS 6214/INSERM 1083, University Bretagne-Loire, 49100 Angers, France
| | - Olivier Le Saux
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96817, USA
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