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Barillaro M, Gonska T. Assessing accuracy of testing and diagnosis in cystic fibrosis. Expert Rev Respir Med 2023:1-13. [PMID: 37190981 DOI: 10.1080/17476348.2023.2213438] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Affiliation(s)
- Malina Barillaro
- Department of Physiology, University of Toronto, Toronto ON, Canada
- Translational Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Tanja Gonska
- Translational Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, University of Toronto, Toronto ON, Canada
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Sermet-Gaudelus I, Girodon E, Vermeulen F, Solomon G, Melotti P, Graeber S, Bronsveld I, Rowe S, Wilschanski M, Tümmler B, Cutting G, Gonska T. ECFS standards of care on CFTR-related disorders: Diagnostic criteria of CFTR dysfunction. J Cyst Fibros 2022; 21:922-936. [DOI: 10.1016/j.jcf.2022.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 09/06/2022] [Accepted: 09/14/2022] [Indexed: 11/06/2022]
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ECFS standards of care on CFTR-related disorders: Updated diagnostic criteria. J Cyst Fibros 2022; 21:908-921. [DOI: 10.1016/j.jcf.2022.09.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 09/27/2022] [Accepted: 09/28/2022] [Indexed: 11/07/2022]
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Guimbellot J, Sharma J, Rowe SM. Toward inclusive therapy with CFTR modulators: Progress and challenges. Pediatr Pulmonol 2017; 52:S4-S14. [PMID: 28881097 PMCID: PMC6208153 DOI: 10.1002/ppul.23773] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 06/29/2017] [Indexed: 12/29/2022]
Abstract
Cystic fibrosis is caused by gene mutations that result in an abnormal Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein on the surface of cells. CFTR modulators are a novel class of drugs that directly target the molecular defect. CFTR modulators include potentiators that result in improved activity of the channel; correctors that help the protein traffic to the cell surface properly; and readthrough agents that restore full-length CFTR by suppression of premature termination codons, among other novel classes more recently established. While some of these drugs, CFTR potentiators in particular, have provided remarkable improvements for CF patients, others have yet to achieve profoundly improved outcomes, and many CF patients are not yet impacted by CFTR modulators due to lack of knowledge regarding susceptibility of their mutations to treatment. One limitation to expanding these types of therapies to the maximum number of patients with CF is the lack of rigorously validated clinical biomarkers that can determine efficacy on an individual basis, as well as few pre-clinical tools that can predict whether an individual with a rare combination of mutant alleles will respond to a particular CFTR modulator regimen. In this review, we discuss the various groups of CFTR modulators and their status in clinical development, as well as address the current literature on biomarkers, pre-clinical cell-based tools, and the role of pharmacometrics in creating therapeutic strategies to improve the lives of all patients with cystic fibrosis, regardless of their specific mutation.
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Affiliation(s)
- Jennifer Guimbellot
- Departments of Pediatrics, The University of Alabama at Birmingham, Birmingham, Alabama
- Gregory Fleming James Cystic Fibrosis Research Center, The University of Alabama at Birmingham, Birmingham, Alabama
| | - Jyoti Sharma
- Gregory Fleming James Cystic Fibrosis Research Center, The University of Alabama at Birmingham, Birmingham, Alabama
- Cell Developmental and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama
| | - Steven M. Rowe
- Departments of Pediatrics, The University of Alabama at Birmingham, Birmingham, Alabama
- Gregory Fleming James Cystic Fibrosis Research Center, The University of Alabama at Birmingham, Birmingham, Alabama
- Cell Developmental and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama
- Departments of Medicine, The University of Alabama at Birmingham, Birmingham, Alabama
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Comparison of Nasal Potential Difference and Intestinal Current Measurements as Surrogate Markers for CFTR Function. J Pediatr Gastroenterol Nutr 2016; 63:e92-e97. [PMID: 27496797 DOI: 10.1097/mpg.0000000000001366] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVES Nasal potential difference (NPD) measurement is part of the diagnostic criteria for cystic fibrosis (CF) and now used routinely as an endpoint in clinical trials of correcting the basic defect in CF. Intestinal current measurement (ICM), measured ex vivo on a rectal biopsy, has been used to study cystic fibrosis transmembrane conductance regulator (CFTR) function but has not been compared to NPD in the same subject in adults and children. The aim of the study is to evaluate the potential usefulness of ICM as a marker of CFTR function for treatment studies compared NPD in patients with CF and in healthy control subjects. METHODS ICM and NPD were performed on healthy controls and patients with CF. The healthy adults were individuals undergoing routine screening colonoscopy at the Beth Israel Deaconess Medical Center. The healthy children were undergoing colonoscopy for suspicion of inflammation in Hadassah Hebrew University Medical Center. The CF adults were recruited from Boston Children's Hospital CF Center and CF Center Worcester Mass, the children with CF from Hadassah CF Center. RESULTS ICM measurements in healthy control subjects (n = 16) demonstrated a mean (±SE) carbachol response of 16.0 (2.2) μA/cm, histamine response of 13.2 (2.1) μA/cm and a forskolin response of 6.3 (2.0) μA/cm. Basal NPD of -15.9 (1.9) and response to Cl free + isoproterenol of -13.8 (2.0). These responses were inverted in CF subjects (n = 12) for ICM parameters with carbachol response of -3.0 (0.5) μA/cm, histamine -1.0 (0.8) μA/cm and a forskolin response of 0.5 (0.3) and also for NPD parameters; basal NPD of -42.2 (4.3) and response to Cl free + isoproterenol of 4.3 (0.7). Pearson correlation test showed the comparability of ICM and NPD in assessing CFTR function. CONCLUSIONS ICM is equivalent to NPD in the ability to distinguish patients with CF from controls and could be used as surrogate markers of CFTR activity in treatment protocols.
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Feinstein Y, Yerushalmi B, Loewenthal N, Alkrinawi S, Birk OS, Parvari R, Hershkovitz E. Natural history and clinical manifestations of hyponatremia and hyperchlorhidrosis due to carbonic anhydrase XII deficiency. Horm Res Paediatr 2015; 81:336-42. [PMID: 24714577 DOI: 10.1159/000358327] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 01/03/2014] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION We identified patients of Bedouin origin with a mutation in carbonic anhydrase XII (CA XII) leading to hyponatremia due to excessive salt loss via sweat. METHODS The medical records of patients were reviewed for clinical and laboratory data. RESULTS A total of 11 subjects were identified; 7 symptomatic patients presented with hyponatremic dehydration in infancy. Screening of the entire kindred identified 4 asymptomatic individuals with elevated sweat chloride. All symptomatic patients had failure to thrive and moderate-severe hyponatremia (106-124 mmol·l(-1)); 6 had hypochloremia (79-94 mmol·l(-1)). All asymptomatic subjects had normal or near-normal serum sodium and chloride concentrations. Both symptomatic and asymptomatic subjects had normal renal functions and normal cortisol response on low-dose ACTH test. All symptomatic patients were treated by dietary salt, which prevents episodes of hyponatremic dehydration and promotes growth. At follow-up, the chief complaints remained heat intolerance, accumulation of salt precipitates on the face and hyperhidrosis. No evidence for chronic renal, respiratory, gastrointestinal or fertility abnormalities was found. CONCLUSION Recognizing this newly described entity and differentiating it from cystic fibrosis and pseudohypoaldosteronism are important. Patients with CA XII mutations should be followed even after early childhood, especially in hot temperatures and intense physical activity.
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Affiliation(s)
- Yael Feinstein
- Pediatric Endocrinology Unit, Soroka Medical Center, Faculty of Health Sciences, Beer Sheva, Israel
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Rowe SM, Liu B, Hill A, Hathorne H, Cohen M, Beamer JR, Accurso FJ, Dong Q, Ordoñez CL, Stone AJ, Olson ER, Clancy JP. Optimizing nasal potential difference analysis for CFTR modulator development: assessment of ivacaftor in CF subjects with the G551D-CFTR mutation. PLoS One 2013; 8:e66955. [PMID: 23922647 PMCID: PMC3724869 DOI: 10.1371/journal.pone.0066955] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 05/13/2013] [Indexed: 11/18/2022] Open
Abstract
Nasal potential difference (NPD) is used as a biomarker of the cystic fibrosis transmembrane conductance regulator (CFTR) and epithelial sodium channel (ENaC) activity. We evaluated methods to detect changes in chloride and sodium transport by NPD based on a secondary analysis of a Phase II CFTR-modulator study. Thirty-nine subjects with CF who also had the G551D-CFTR mutation were randomized to receive ivacaftor (Kalydeco™; also known as VX-770) in four doses or placebo twice daily for at least 14 days. All data were analyzed by a single investigator who was blinded to treatment assignment. We compared three analysis methods to determine the best approach to quantify changes in chloride and sodium transport: (1) the average of both nostrils; (2) the most-polarized nostril at each visit; and (3) the most-polarized nostril at screening carried forward. Parameters of ion transport included the PD change with zero chloride plus isoproterenol (CFTR activity), the basal PD, Ringer's PD, and change in PD with amiloride (measurements of ENaC activity), and the delta NPD (measuring CFTR and ENaC activity). The average and most-polarized nostril at each visit were most sensitive to changes in chloride and sodium transport, whereas the most-polarized nostril at screening carried forward was less discriminatory. Based on our findings, NPD studies should assess both nostrils rather than a single nostril. We also found that changes in CFTR activity were more readily detected than changes in ENaC activity, and that rigorous standardization was associated with relatively good within-subject reproducibility in placebo-treated subjects (±2.8 mV). Therefore, we have confirmed an assay of reasonable reproducibility for detecting chloride-transport improvements in response to CFTR modulation.
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Affiliation(s)
- Steven M. Rowe
- University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Bo Liu
- University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Aubrey Hill
- University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Heather Hathorne
- University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Morty Cohen
- Seattle Children's Hospital, Seattle, Washington, United States of America
| | - John R. Beamer
- Seattle Children's Hospital, Seattle, Washington, United States of America
| | - Frank J. Accurso
- University of Colorado Denver, Aurora, Colorado, United States of America
| | - Qunming Dong
- Vertex Pharmaceuticals Incorporated, Cambridge, Massachusetts, United States of America
| | - Claudia L. Ordoñez
- Vertex Pharmaceuticals Incorporated, Cambridge, Massachusetts, United States of America
| | - Anne J. Stone
- Vertex Pharmaceuticals Incorporated, Cambridge, Massachusetts, United States of America
| | - Eric R. Olson
- Vertex Pharmaceuticals Incorporated, Cambridge, Massachusetts, United States of America
| | - John P. Clancy
- Cincinnati Children's Hospital Medical Center and the University of Cincinnati, Cincinnati, Ohio, United States of America
- * E-mail:
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Abstract
Several diseases have been clinically or genetically related to cystic fibrosis (CF), but a consensus definition is lacking. Here, we present a proposal for consensus guidelines on cystic fibrosis transmembrane conductance regulator (CFTR)-related disorders (CFTR-RDs), reached after expert discussion and two dedicated workshops. A CFTR-RD may be defined as "a clinical entity associated with CFTR dysfunction that does not fulfil diagnostic criteria for CF". The utility of sweat testing, mutation analysis, nasal potential difference, and/or intestinal current measurement for the differential diagnosis of CF and CFTR-RD is discussed. Algorithms which use genetic and functional diagnostic tests to distinguish CF and CFTR-RDs are presented. According to present knowledge, congenital bilateral absence of vas deferens (CBAVD), acute recurrent or chronic pancreatitis and disseminated bronchiectasis, all with CFTR dysfunction, are CFTR-RDs.
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Feldshtein M, Elkrinawi S, Yerushalmi B, Marcus B, Vullo D, Romi H, Ofir R, Landau D, Sivan S, Supuran CT, Birk OS. Hyperchlorhidrosis caused by homozygous mutation in CA12, encoding carbonic anhydrase XII. Am J Hum Genet 2010; 87:713-20. [PMID: 21035102 DOI: 10.1016/j.ajhg.2010.10.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 10/08/2010] [Accepted: 10/12/2010] [Indexed: 12/22/2022] Open
Abstract
Excessive chloride secretion in sweat (hyperchlorhidrosis), leading to a positive sweat test, is most commonly indicative of cystic fibrosis yet is found also in conjunction with various metabolic, endocrine, and dermatological disorders. There is conflicting evidence regarding the existence of autosomal-recessive hyperchlorhidrosis. We now describe a consanguineous Israeli Bedouin kindred with autosomal-recessive hyperchlohidrosis whose sole symptoms are visible salt precipitates after sweating, a preponderance to hyponatremic dehydration, and poor feeding and slow weight gain at infancy. Through genome-wide linkage analysis, we demonstrate that the phenotype is due to a homozygous mutation in CA12, encoding carbonic anhydrase XII. The mutant (c.427G>A [p.Glu143Lys]) protein showed 71% activity of the wild-type enzyme for catalyzing the CO₂ hydration to bicarbonate and H(+), and it bound the clinically used sulfonamide inhibitor acetazolamide with high affinity (K(I) of 10 nM). Unlike the wild-type enzyme, which is not inhibited by chloride, bromide, or iodide (K(I)s of 73-215 mM), the mutant is inhibited in the submicromolar range by these anions (K(I)s of 0.37-0.73 mM).
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Sermet-Gaudelus I, Girodon E, Sands D, Stremmler N, Vavrova V, Deneuville E, Reix P, Bui S, Huet F, Lebourgeois M, Munck A, Iron A, Skalicka V, Bienvenu T, Roussel D, Lenoir G, Bellon G, Sarles J, Macek M, Roussey M, Fajac I, Edelman A. Clinical Phenotype and Genotype of Children with Borderline Sweat Test and Abnormal Nasal Epithelial Chloride Transport. Am J Respir Crit Care Med 2010; 182:929-36. [DOI: 10.1164/rccm.201003-0382oc] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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Middleton PG, House HH. Measurement of airway ion transport assists the diagnosis of cystic fibrosis. Pediatr Pulmonol 2010; 45:789-95. [PMID: 20597077 DOI: 10.1002/ppul.21253] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The nasal potential difference (PD) demonstrates the increased Na absorption and decreased Cl secretion typically found in cystic fibrosis (CF). It provides useful information for diagnostic purposes and measures the effect of new treatments on the ion transport defects found in CF. This study summarizes the nasal PD results in the respiratory tract of different groups of subjects, examines the responses in squamous epithelia and evaluates new ways to consider nasal PD results.Nasal PD was tested using the standard protocol of baseline, amiloride, low chloride, and isoproterenol solutions in 40 healthy non-CF volunteers, 46 CF subjects, and 78 subjects referred for investigation of possible CF. Nasal PD was also measured in the squamous epithelium at the anterior nares in six non-CF subjects.Baseline PD was elevated in the CF (47.5 (1.7) mV) compared with non-CF subjects: (14.0 (0.8) mV, P < 0.00001). Combined [Cl + Isop] responses were smaller in the CF (-0.1 (0.4) mV) compared with the non-CF subjects (26.2 (1.2) mV, P < 0.00001). In the diagnostic cohort 58 were given a non-CF diagnosis, 16 had CF confirmed, but 4 remained indeterminate. Separate consideration of Na and Cl transport was easily portrayed through X-Y plots. Finally, the nasal PD responses of squamous epithelium showed high baseline values, but little response to amiloride and low chloride solutions.The nasal PD provides useful information in the diagnostic algorithm of CF, and in the delineation of the two ion transport defects characteristically found in the respiratory epithelium. Avoidance of the squamous epithelium remains an important consideration for those performing and interpreting nasal PD responses.
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Affiliation(s)
- Peter G Middleton
- Cystic Fibrosis Unit, Ludwig Engel Centre for Respiratory Research, Westmead Millennium Institute, University of Sydney at Westmead, Westmead, NSW, Australia.
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Taylor CJ, Hardcastle J, Southern KW. Physiological measurements confirming the diagnosis of cystic fibrosis: the sweat test and measurements of transepithelial potential difference. Paediatr Respir Rev 2009; 10:220-6. [PMID: 19879513 DOI: 10.1016/j.prrv.2009.05.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Revised: 05/19/2009] [Accepted: 05/26/2009] [Indexed: 11/15/2022]
Abstract
Post-natal screening allied with genetic mutation testing has altered our perception of cystic fibrosis (CF) as a clinical entity. Increasingly, infants identified through screening programmes have few or no symptoms or present with atypical forms of the disease. We review how the sweat test has evolved to be the gold standard for confirming the diagnosis of CF and examine its limitations. Other physiological measurements, including nasal potential difference and intestinal current measurement, which might aid in establishing the diagnosis, particularly in patients exhibiting a mild phenotype, are also considered.
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Affiliation(s)
- C J Taylor
- Sheffield Paediatric Cystic Fibrosis Centre, Sheffield, Academic Unit of Child Health, University of Sheffield, UK.
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House HH, Middleton PG. Impact of different chloride and glucose solutions on nasal potential difference. Pediatr Pulmonol 2009; 44:645-8. [PMID: 19514053 DOI: 10.1002/ppul.21032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
INTRODUCTION The nasal potential difference (nasal PD) technique can provide useful diagnostic information and can be used to assess the physiological effect of new treatments for cystic fibrosis (CF). In preparation for multi center trials of new CF treatments, many groups worldwide have sought to standardize the protocol, but subtle differences in solution composition remain. This article has compared the effect of different chloride and glucose concentrations on the PD. METHODS Following pre-treatment with amiloride to block sodium absorption, the effect of 0 mM versus 6 mM chloride was compared in six non-CF and six CF subjects. In a separate series of experiments, the effect of glucose on baseline PD was examined in the range of 0-20 mM. RESULTS Following amiloride pre-treatment, the change from 6 to 0 mM chloride increased the PD by approximately 2 mV in the non-CF subjects; the reverse protocol decreased PD by a similar amount. As expected, little change in PD occurred in the CF subjects. Changing the glucose concentration between 0, 10, and 20 mM had little effect on nasal PD in non-CF and CF subjects. CONCLUSION The use of 0 mM chloride gives responses in the non-CF subjects, which are approximately 2 mV greater than protocols which use low (6 mM) chloride. Different glucose concentrations appear to exert little effect on baseline PD, suggesting that electrogenic glucose transport plays a limited role in airway transport at rest.
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Affiliation(s)
- Hugh H House
- Cystic Fibrosis Unit, Ludwig Engel Centre for Respiratory Research, Westmead Millennium Institute, University of Sydney at Westmead, Westmead, NSW 2145, Australia
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