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Lundkvist S, Niaziorimi F, Szeri F, Caffet M, Terry SF, Johansson G, Jansen RS, van de Wetering K. A new enzymatic assay to quantify inorganic pyrophosphate in plasma. Anal Bioanal Chem 2023; 415:481-492. [PMID: 36400967 PMCID: PMC9839608 DOI: 10.1007/s00216-022-04430-8] [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: 06/10/2022] [Revised: 11/03/2022] [Accepted: 11/08/2022] [Indexed: 11/21/2022]
Abstract
Inorganic pyrophosphate (PPi) is a crucial extracellular mineralization regulator. Low plasma PPi concentrations underlie the soft tissue calcification present in several rare hereditary mineralization disorders as well as in more common conditions like chronic kidney disease and diabetes. Even though deregulated plasma PPi homeostasis is known to be linked to multiple human diseases, there is currently no reliable assay for its quantification. We here describe a PPi assay that employs the enzyme ATP sulfurylase to convert PPi into ATP. Generated ATP is subsequently quantified by firefly luciferase-based bioluminescence. An internal ATP standard was used to correct for sample-specific interference by matrix compounds on firefly luciferase activity. The assay was validated and shows excellent precision (< 3.5%) and accuracy (93-106%) of PPi spiked into human plasma samples. We found that of several anticoagulants tested only EDTA effectively blocked conversion of ATP into PPi in plasma after blood collection. Moreover, filtration over a 300,000-Da molecular weight cut-off membrane reduced variability of plasma PPi and removed ATP present in a membrane-enclosed compartment, possibly platelets. Applied to plasma samples of wild-type and Abcc6-/- rats, an animal model with established low circulating levels of PPi, the new assay showed lower variability than the assay that was previously in routine use in our laboratory. In conclusion, we here report a new and robust assay to determine PPi concentrations in plasma, which outperforms currently available assays because of its high sensitivity, precision, and accuracy.
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Affiliation(s)
- Stefan Lundkvist
- Department of Dermatology and Cutaneous Biology, Jefferson Institute of Molecular Medicine and PXE International Center of Excellence in Research and Clinical Care, Sidney Kimmel Medical College, Thomas Jefferson University, 233 S 10th Street, PA, 19107, Philadelphia, USA
- Department of Chemistry (BMC), Uppsala University, Uppsala, Sweden
| | - Fatemeh Niaziorimi
- Department of Dermatology and Cutaneous Biology, Jefferson Institute of Molecular Medicine and PXE International Center of Excellence in Research and Clinical Care, Sidney Kimmel Medical College, Thomas Jefferson University, 233 S 10th Street, PA, 19107, Philadelphia, USA
| | - Flora Szeri
- Department of Dermatology and Cutaneous Biology, Jefferson Institute of Molecular Medicine and PXE International Center of Excellence in Research and Clinical Care, Sidney Kimmel Medical College, Thomas Jefferson University, 233 S 10th Street, PA, 19107, Philadelphia, USA
- Research Centre for Natural Sciences, Institute of Enzymology, Budapest, Hungary
- Department of Biochemistry, Semmelweis University, Budapest, Hungary
| | | | | | - Gunnar Johansson
- Department of Chemistry (BMC), Uppsala University, Uppsala, Sweden
| | - Robert S Jansen
- Department of Microbiology, Radboud University, Nijmegen, The Netherlands
| | - Koen van de Wetering
- Department of Dermatology and Cutaneous Biology, Jefferson Institute of Molecular Medicine and PXE International Center of Excellence in Research and Clinical Care, Sidney Kimmel Medical College, Thomas Jefferson University, 233 S 10th Street, PA, 19107, Philadelphia, USA.
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2
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Bax M, Romanov V, Junday K, Giannoulatou E, Martinac B, Kovacic JC, Liu R, Iismaa SE, Graham RM. Arterial dissections: Common features and new perspectives. Front Cardiovasc Med 2022; 9:1055862. [PMID: 36561772 PMCID: PMC9763901 DOI: 10.3389/fcvm.2022.1055862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 11/16/2022] [Indexed: 12/12/2022] Open
Abstract
Arterial dissections, which involve an abrupt tear in the wall of a major artery resulting in the intramural accumulation of blood, are a family of catastrophic disorders causing major, potentially fatal sequelae. Involving diverse vascular beds, including the aorta or coronary, cervical, pulmonary, and visceral arteries, each type of dissection is devastating in its own way. Traditionally they have been studied in isolation, rather than collectively, owing largely to the distinct clinical consequences of dissections in different anatomical locations - such as stroke, myocardial infarction, and renal failure. Here, we review the shared and unique features of these arteriopathies to provide a better understanding of this family of disorders. Arterial dissections occur commonly in the young to middle-aged, and often in conjunction with hypertension and/or migraine; the latter suggesting they are part of a generalized vasculopathy. Genetic studies as well as cellular and molecular investigations of arterial dissections reveal striking similarities between dissection types, particularly their pathophysiology, which includes the presence or absence of an intimal tear and vasa vasorum dysfunction as a cause of intramural hemorrhage. Pathway perturbations common to all types of dissections include disruption of TGF-β signaling, the extracellular matrix, the cytoskeleton or metabolism, as evidenced by the finding of mutations in critical genes regulating these processes, including LRP1, collagen genes, fibrillin and TGF-β receptors, or their coupled pathways. Perturbances in these connected signaling pathways contribute to phenotype switching in endothelial and vascular smooth muscle cells of the affected artery, in which their physiological quiescent state is lost and replaced by a proliferative activated phenotype. Of interest, dissections in various anatomical locations are associated with distinct sex and age predilections, suggesting involvement of gene and environment interactions in disease pathogenesis. Importantly, these cellular mechanisms are potentially therapeutically targetable. Consideration of arterial dissections as a collective pathology allows insight from the better characterized dissection types, such as that involving the thoracic aorta, to be leveraged to inform the less common forms of dissections, including the potential to apply known therapeutic interventions already clinically available for the former.
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Affiliation(s)
- Monique Bax
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
- UNSW Medicine and Health, UNSW Sydney, Kensington, NSW, Australia
| | - Valentin Romanov
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
- UNSW Medicine and Health, UNSW Sydney, Kensington, NSW, Australia
| | - Keerat Junday
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
- UNSW Medicine and Health, UNSW Sydney, Kensington, NSW, Australia
| | - Eleni Giannoulatou
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
- UNSW Medicine and Health, UNSW Sydney, Kensington, NSW, Australia
| | - Boris Martinac
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
- UNSW Medicine and Health, UNSW Sydney, Kensington, NSW, Australia
| | - Jason C. Kovacic
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
- UNSW Medicine and Health, UNSW Sydney, Kensington, NSW, Australia
- St. Vincent’s Hospital, Darlinghurst, NSW, Australia
- Icahn School of Medicine at Mount Sinai, Cardiovascular Research Institute, New York, NY, United States
| | - Renjing Liu
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
- UNSW Medicine and Health, UNSW Sydney, Kensington, NSW, Australia
| | - Siiri E. Iismaa
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
- UNSW Medicine and Health, UNSW Sydney, Kensington, NSW, Australia
| | - Robert M. Graham
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
- UNSW Medicine and Health, UNSW Sydney, Kensington, NSW, Australia
- St. Vincent’s Hospital, Darlinghurst, NSW, Australia
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3
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Szeri F, Miko A, Navasiolava N, Kaposi A, Verschuere S, Molnar B, Li Q, Terry SF, Boraldi F, Uitto J, van de Wetering K, Martin L, Quaglino D, Vanakker OM, Tory K, Aranyi T. The pathogenic c.1171A>G (p.Arg391Gly) and c.2359G>A (p.Val787Ile) ABCC6 variants display incomplete penetrance causing pseudoxanthoma elasticum in a subset of individuals. Hum Mutat 2022; 43:1872-1881. [PMID: 36317459 PMCID: PMC9772137 DOI: 10.1002/humu.24498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 09/30/2022] [Accepted: 10/24/2022] [Indexed: 11/06/2022]
Abstract
ABCC6 promotes ATP efflux from hepatocytes to bloodstream. ATP is metabolized to pyrophosphate, an inhibitor of ectopic calcification. Pathogenic variants of ABCC6 cause pseudoxanthoma elasticum, a highly variable recessive ectopic calcification disorder. Incomplete penetrance may initiate disease heterogeneity, hence symptoms may not, or differently manifest in carriers. Here, we investigated whether incomplete penetrance is a source of heterogeneity in pseudoxanthoma elasticum. By integrating clinical and genetic data of 589 patients, we created the largest European cohort. Based on allele frequency alterations, we identified two incomplete penetrant pathogenic variants, c.2359G>A (p.Val787Ile) and c.1171A>G (p.Arg391Gly), with 6.5% and 2% penetrance, respectively. However, when penetrant, the c.1171A>G (p.Arg391Gly) manifested a clinically unaltered severity. After applying in silico and in vitro characterization, we suggest that incomplete penetrant variants are only deleterious if a yet unknown interacting partner of ABCC6 is mutated simultaneously. The low penetrance of these variants should be contemplated in genetic counseling.
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Affiliation(s)
- Flora Szeri
- Department of Dermatology and Cutaneous Biology, The Sidney Kimmel Medical College, and The PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA, USA,Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary,Department of Biochemistry, Semmelweis University, Budapest, Hungary
| | - Agnes Miko
- MTA-SE Lendület Nephrogenetic Laboratory, Budapest, Hungary,1st Department of Pediatrics, Semmelweis University, Budapest, Hungary
| | - Nastassia Navasiolava
- PXE Consultation Center, MAGEC Nord Reference Center for Rare Skin Diseases, Angers University Hospital, Angers, France
| | - Ambrus Kaposi
- MTA-SE Lendület Nephrogenetic Laboratory, Budapest, Hungary,1st Department of Pediatrics, Semmelweis University, Budapest, Hungary
| | - Shana Verschuere
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Beatrix Molnar
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary
| | - Qiaoli Li
- Department of Dermatology and Cutaneous Biology, The Sidney Kimmel Medical College, and The PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - Federica Boraldi
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Jouni Uitto
- Department of Dermatology and Cutaneous Biology, The Sidney Kimmel Medical College, and The PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA, USA
| | - Koen van de Wetering
- Department of Dermatology and Cutaneous Biology, The Sidney Kimmel Medical College, and The PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA, USA
| | - Ludovic Martin
- PXE Consultation Center, MAGEC Nord Reference Center for Rare Skin Diseases, Angers University Hospital, Angers, France
| | - Daniela Quaglino
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy,Interuniversity Consortium for Biotechnologies (CIB), Italy
| | | | - Kalman Tory
- MTA-SE Lendület Nephrogenetic Laboratory, Budapest, Hungary,1st Department of Pediatrics, Semmelweis University, Budapest, Hungary
| | - Tamas Aranyi
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary,Department of Molecular Biology, Semmelweis University, Budapest, Hungary.,Corresponding author:
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4
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Serum Calcification Propensity T50 Associates with Disease Severity in Patients with Pseudoxanthoma Elasticum. J Clin Med 2022; 11:jcm11133727. [PMID: 35807012 PMCID: PMC9267205 DOI: 10.3390/jcm11133727] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/21/2022] [Accepted: 06/26/2022] [Indexed: 11/17/2022] Open
Abstract
Pseudoxanthoma elasticum (PXE) is a currently intractable genetic disorder characterized by progressive ectopic calcification in the skin, eyes and arteries. Therapeutic trials in PXE are severely hampered by the lack of reliable biomarkers. Serum calcification propensity T50 is a blood test measuring the functional anticalcifying buffer capacity of serum. Here, we evaluated T50 in PXE patients aiming to investigate its determinants and suitability as a potential biomarker for disease severity. Fifty-seven PXE patients were included in this cross-sectional study, and demographic, clinical, imaging and biochemical data were collected from medical health records. PXE severity was assessed using Phenodex scores. T50 was measured using a validated, nephelometry-based assay. Multivariate models were then created to investigate T50 determinants and associations with disease severity. In short, the mean age of patients was 45.2 years, 68.4% was female and mean serum T50 was 347 min. Multivariate regression analysis identified serum fetuin-A (p < 0.001), phosphorus (p = 0.007) and magnesium levels (p = 0.034) as significant determinants of T50, while no correlations were identified with serum calcium, eGFR, plasma PPi levels or the ABCC6 genotype. After correction for covariates, T50 was found to be an independent determinant of ocular (p = 0.013), vascular (p = 0.013) and overall disease severity (p = 0.016) in PXE. To conclude, shorter serum T50—indicative of a higher calcification propensity—was associated with a more severe phenotype in PXE patients. This study indicates, for the first time, that serum T50 might be a clinically relevant biomarker in PXE and may thus be of importance to future therapeutic trials.
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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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6
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Boraldi F, Murro V, Lofaro FD, Mucciolo DP, Costa S, Pavese L, Quaglino D. Phenotypic Features and Genetic Findings in a Cohort of Italian Pseudoxanthoma Elasticum Patients and Update of the Ophthalmologic Evaluation Score. J Clin Med 2021; 10:2710. [PMID: 34205333 PMCID: PMC8235548 DOI: 10.3390/jcm10122710] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/11/2021] [Accepted: 06/16/2021] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Pseudoxanthoma elasticum (PXE) is a rare ectopic calcification genetic disease mainly caused by ABCC6 rare sequence variants. The clinical phenotype is characterized by typical dermatological, ophthalmological and cardiovascular manifestations, whose frequency and severity are differently reported in the literature. METHODS A retrospective study was performed on 377 PXE patients of Italian origin, clinically evaluated according to the Phenodex Index, who underwent ABCC6 biomolecular analyses. Moreover, 53 PXE patients were further characterized by in-depth ophthalmological examinations. RESULTS A total of 117 different ABCC6 rare sequence variants were detected as being spread through the whole gene. The severity of the clinical phenotype was dependent on age, but it was not influenced by gender or by the type of sequence variants. In-depth ophthalmological examinations focused on the incidences of coquille d'oeuf, comet lesions, pattern dystrophy-like lesions, optic disk drusen and posterior-pole atrophy. Conclusion: Given the large number of patients analyzed, we were able to better evaluate the occurrence of less frequent alterations (e.g., stroke, myocardial infarction, nephrolithiasis). A more detailed description of ophthalmological abnormalities allowed us to stratify patients and better evaluate disease progression, thus suggesting a further update of the PXE score system.
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Affiliation(s)
- Federica Boraldi
- Department of Life Science, University of Modena and Reggio Emilia, Via Campi 287, 41125 Modena, Italy; (F.B.); (F.D.L.); (S.C.)
| | - Vittoria Murro
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Eye Clinic, Viale Pieraccini 6, 50139 Florence, Italy; (V.M.); (D.P.M.); (L.P.)
| | - Francesco Demetrio Lofaro
- Department of Life Science, University of Modena and Reggio Emilia, Via Campi 287, 41125 Modena, Italy; (F.B.); (F.D.L.); (S.C.)
| | - Dario Pasquale Mucciolo
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Eye Clinic, Viale Pieraccini 6, 50139 Florence, Italy; (V.M.); (D.P.M.); (L.P.)
| | - Sonia Costa
- Department of Life Science, University of Modena and Reggio Emilia, Via Campi 287, 41125 Modena, Italy; (F.B.); (F.D.L.); (S.C.)
| | - Laura Pavese
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Eye Clinic, Viale Pieraccini 6, 50139 Florence, Italy; (V.M.); (D.P.M.); (L.P.)
| | - Daniela Quaglino
- Department of Life Science, University of Modena and Reggio Emilia, Via Campi 287, 41125 Modena, Italy; (F.B.); (F.D.L.); (S.C.)
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7
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De Vilder EYG, Martin L, Lefthériotis G, Coucke P, Van Nieuwerburgh F, Vanakker OM. Rare Modifier Variants Alter the Severity of Cardiovascular Disease in Pseudoxanthoma Elasticum: Identification of Novel Candidate Modifier Genes and Disease Pathways Through Mixture of Effects Analysis. Front Cell Dev Biol 2021; 9:612581. [PMID: 34169069 PMCID: PMC8218811 DOI: 10.3389/fcell.2021.612581] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 05/11/2021] [Indexed: 12/30/2022] Open
Abstract
Introduction: Pseudoxanthoma elasticum (PXE), an ectopic mineralization disorder caused by pathogenic ABCC6 variants, is characterized by skin, ocular and cardiovascular (CV) symptoms. Due to striking phenotypic variability without genotype-phenotype correlations, modifier genes are thought to play a role in disease variability. In this study, we evaluated the collective modifying effect of rare variants on the cardiovascular phenotype of PXE. Materials and Methods: Mixed effects of rare variants were assessed by Whole Exome Sequencing in 11 PXE patients with an extreme CV phenotype (mild/severe). Statistical analysis (SKAT-O and C-alpha testing) was performed to identify new modifier genes for the CV PXE phenotype and enrichment analysis for genes significantly associated with the severe cohort was used to evaluate pathway and gene ontology features. Results Respectively 16 (SKAT-O) and 74 (C-alpha) genes were significantly associated to the severe cohort. Top significant genes could be stratified in 3 groups–calcium homeostasis, association with vascular disease and induction of apoptosis. Comparative analysis of both analyses led to prioritization of four genes (NLRP1, SELE, TRPV1, and CSF1R), all signaling through IL-1B. Conclusion This study explored for the first time the cumulative effect of rare variants on the severity of cardiovascular disease in PXE, leading to a panel of novel candidate modifier genes and disease pathways. Though further validation is essential, this panel may aid in risk stratification and genetic counseling of PXE patients and will help to gain new insights in the PXE pathophysiology.
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Affiliation(s)
- Eva Y G De Vilder
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.,The Research Foundation - Flanders, Ghent, Belgium.,Department of Ophthalmology, Ghent University Hospital, Ghent, Belgium
| | - Ludovic Martin
- Department of Dermatology, Angers University Hospital, Angers, France
| | - Georges Lefthériotis
- Department of Vascular Physiology and Sports Medicine, Angers University, Angers, France
| | - Paul Coucke
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.,Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Filip Van Nieuwerburgh
- Department of Pharmaceutics, Laboratory of Pharmaceutical Biotechnology, Ghent University, Ghent, Belgium
| | - Olivier M Vanakker
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.,Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
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8
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Nollet L, Campens L, De Zaeytijd J, Leroy B, Hemelsoet D, Coucke PJ, Vanakker OM. Clinical and subclinical findings in heterozygous ABCC6 carriers: results from a Belgian cohort and clinical practice guidelines. J Med Genet 2021; 59:496-504. [PMID: 33820832 DOI: 10.1136/jmedgenet-2020-107565] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 02/23/2021] [Accepted: 03/06/2021] [Indexed: 12/12/2022]
Abstract
BACKGROUND Biallelic pathogenic variants in the ATP-binding cassette subfamily C member 6 (ABCC6) gene cause pseudoxanthoma elasticum, a multisystemic ectopic calcification disorder, while heterozygous ABCC6 variants are associated with an increased risk of cardiovascular and cerebrovascular disease. As the prevalence of pathogenic ABCC6 variants in the general population is estimated at ~1%, identifying additional ABCC6-related (sub)clinical manifestations in heterozygous carriers is of the utmost importance to reduce this burden of disease. Here, we present a large Belgian cohort of heterozygous ABCC6 carriers with comprehensive clinical, biochemical and imaging data. Based on these results, we formulate clinical practice guidelines regarding screening, preventive measures and follow-up of ABCC6 carriers. METHODS The phenotype of 56 individuals carrying heterozygous pathogenic ABCC6 variants was assessed using clinical (eg, detailed ophthalmological examinations), biochemical, imaging (eg, cardiovascular and abdominal ultrasound) and genetic data. Clinical practice guidelines were then drawn up. RESULTS We found that ABCC6 heterozygosity is associated with distinct retinal alterations ('comet-like') (24%), high prevalence of hypercholesterolaemia (>75%) and diastolic dysfunction (33%), accelerated lower limb atherosclerosis and medial vascular disease, abdominal organ calcification (26%) and testicular microlithiasis (28%), though with highly variable expression. CONCLUSION In this study, we delineated the multisystemic ABCC6 heterozygosity phenotype characterised by retinal alterations, aberrant lipid metabolism, diastolic dysfunction and increased vascular, abdominal and testicular calcifications. Our clinical practice guidelines aimed to improve early diagnosis, treatment and follow-up of ABCC6-related health problems.
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Affiliation(s)
- Lukas Nollet
- Center for Medical Genetics, University Hospital Ghent, Ghent, Belgium.,Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Laurence Campens
- Department of Cardiology, University Hospital Ghent, Ghent, Belgium
| | - Julie De Zaeytijd
- Department of Ophthalmology, University Hospital Ghent, Ghent, Belgium
| | - Bart Leroy
- Department of Ophthalmology, University Hospital Ghent, Ghent, Belgium.,Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | | | - Paul J Coucke
- Center for Medical Genetics, University Hospital Ghent, Ghent, Belgium.,Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Olivier M Vanakker
- Center for Medical Genetics, University Hospital Ghent, Ghent, Belgium .,Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
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9
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Bartstra JW, Risseeuw S, de Jong PA, van Os B, Kalsbeek L, Mol C, Baas AF, Verschuere S, Vanakker O, Florijn RJ, Hendrikse J, Mali W, Imhof S, Ossewaarde-van Norel J, van Leeuwen R, Spiering W. Genotype-phenotype correlation in pseudoxanthoma elasticum. Atherosclerosis 2021; 324:18-26. [PMID: 33812167 DOI: 10.1016/j.atherosclerosis.2021.03.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/26/2021] [Accepted: 03/10/2021] [Indexed: 12/20/2022]
Abstract
BACKGROUND AND AIMS Pseudoxanthoma elasticum (PXE) is caused by variants in the ABCC6 gene. It results in calcification in the skin, peripheral arteries and the eyes, but has considerable phenotypic variability. We investigated the association between the ABCC6 genotype and calcification and clinical phenotypes in these different organs. METHODS ABCC6 sequencing was performed in 289 PXE patients. Genotypes were grouped as two truncating, mixed, or two non-truncating variants. Arterial calcification mass was quantified on whole body, low dose CT scans; and peripheral arterial disease was measured with the ankle brachial index after treadmill test. The presence of pseudoxanthoma in the skin was systematically scored. Ophthalmological phenotypes were the length of angioid streaks as a measure of Bruchs membrane calcification, the presence of choroidal neovascularizations, severity of macular atrophy and visual acuity. Regression models were built to test the age and sex adjusted genotype-phenotype association. RESULTS 158 patients (median age 51 years) had two truncating variants, 96 (median age 54 years) a mixed genotype, 18 (median age 47 years) had two non-truncating variants. The mixed genotype was associated with lower peripheral (β: 0.39, 95%CI:-0.62;-0.17) and total (β: 0.28, 95%CI:-0.47;-0.10) arterial calcification mass scores, and lower prevalence of choroidal neovascularizations (OR: 0.41 95%CI:0.20; 0.83) compared to two truncating variants. No association with pseudoxanthomas was found. CONCLUSIONS PXE patients with a mixed genotype have less severe arterial and ophthalmological phenotypes than patients with two truncating variants in the ABCC6 gene. Research into environmental and genetic modifiers might provide further insights into the unexplained phenotypic variability.
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Affiliation(s)
- Jonas W Bartstra
- Department of Radiology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Sara Risseeuw
- Department of Ophthalmology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Pim A de Jong
- Department of Radiology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Bram van Os
- Department of Radiology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Lianne Kalsbeek
- Department of Radiology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Chris Mol
- Department of Radiology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Annette F Baas
- Department of Genetics, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Shana Verschuere
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Olivier Vanakker
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Ralph J Florijn
- Department of Clinical Genetics, Academic Medical Center, Amsterdam, the Netherlands
| | - Jeroen Hendrikse
- Department of Radiology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Willem Mali
- Department of Radiology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Saskia Imhof
- Department of Ophthalmology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | | | - Redmer van Leeuwen
- Department of Ophthalmology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Wilko Spiering
- Department of Vascular Medicine, University Medical Center Utrecht, Utrecht University, the Netherlands.
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10
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Autofluorescence Imaging of the Skin Is an Objective Non-Invasive Technique for Diagnosing Pseudoxanthoma Elasticum. Diagnostics (Basel) 2021; 11:diagnostics11020260. [PMID: 33567497 PMCID: PMC7915757 DOI: 10.3390/diagnostics11020260] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/03/2021] [Accepted: 02/04/2021] [Indexed: 01/05/2023] Open
Abstract
Pseudoxanthoma elasticum (PXE) is a rare multisystemic autosomal recessive connective tissue disease. In most cases, skin manifestations of PXE are the first to develop, followed later by severe ocular and cardiovascular complications. In our present study, in addition to dermoscopy, we introduced novel techniques, autofluorescence (AF) and diffuse reflectance (DR) imaging for the assessment of affected skin sites of five PXE patients. PXE-affected skin areas in most skin sites showed a previously observed pattern upon dermoscopic examination. With the novel imaging, PXE-affected skin lesions displayed high AF intensity. During our measurements, significantly higher mean, minimum and maximum AF intensity values were found in areas of PXE-affected skin when compared to uninvolved skin. Conversely, images acquired with the use of 660 and 940 nm illumination showed no mentionable difference. Our results demonstrate that AF imaging may be used in the in vivo diagnostics and quantification of the severity of the skin lesions of PXE patients. In addition, it is a safe, fast and cost-effective diagnostic method. AF imaging may be also used to objectively monitor the efficacy of the possible novel therapeutic approaches of PXE in the future.
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11
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Verschuere S, Van Gils M, Nollet L, Vanakker OM. From membrane to mineralization: the curious case of the ABCC6 transporter. FEBS Lett 2020; 594:4109-4133. [PMID: 33131056 DOI: 10.1002/1873-3468.13981] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 10/12/2020] [Accepted: 10/16/2020] [Indexed: 12/13/2022]
Abstract
ATP-binding cassette subfamily C member 6 gene/protein (ABCC6) is an ATP-dependent transmembrane transporter predominantly expressed in the liver and the kidney. ABCC6 first came to attention in human medicine when it was discovered in 2000 that mutations in its encoding gene, ABCC6, caused the autosomal recessive multisystemic mineralization disease pseudoxanthoma elasticum (PXE). Since then, the physiological and pathological roles of ABCC6 have been the subject of intense research. In the last 20 years, significant findings have clarified ABCC6 structure as well as its physiological role in mineralization homeostasis in humans and animal models. Yet, several facets of ABCC6 biology remain currently incompletely understood, ranging from the precise nature of its substrate(s) to the increasingly complex molecular genetics. Nonetheless, advances in our understanding of pathophysiological mechanisms causing mineralization lead to several treatment options being suggested or already tested in pilot clinical trials for ABCC6 deficiency. This review highlights current knowledge of ABCC6 and the challenges ahead, particularly the attempts to translate basic science into clinical practice.
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Affiliation(s)
- Shana Verschuere
- Center for Medical Genetics, Ghent University Hospital, Belgium.,Department of Biomolecular Medicine, Ghent University, Belgium.,Ectopic Mineralization Research Group Ghent, Ghent, Belgium
| | - Matthias Van Gils
- Center for Medical Genetics, Ghent University Hospital, Belgium.,Department of Biomolecular Medicine, Ghent University, Belgium.,Ectopic Mineralization Research Group Ghent, Ghent, Belgium
| | - Lukas Nollet
- Center for Medical Genetics, Ghent University Hospital, Belgium.,Department of Biomolecular Medicine, Ghent University, Belgium.,Ectopic Mineralization Research Group Ghent, Ghent, Belgium
| | - Olivier M Vanakker
- Center for Medical Genetics, Ghent University Hospital, Belgium.,Department of Biomolecular Medicine, Ghent University, Belgium.,Ectopic Mineralization Research Group Ghent, Ghent, Belgium
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