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Durie P, Baillargeon JD, Bouchard S, Donnellan F, Zepeda-Gomez S, Teshima C. Diagnosis and management of pancreatic exocrine insufficiency (PEI) in primary care: consensus guidance of a Canadian expert panel. Curr Med Res Opin 2018; 34:25-33. [PMID: 28985688 DOI: 10.1080/03007995.2017.1389704] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Pancreatic exocrine insufficiency (PEI) results in maldigestion due to inadequate activity of pancreatic enzymes in the small bowel. PEI can arise from a variety of medical conditions that reduce enzyme synthesis within the pancreatic parenchyma or from secondary factors that may occur despite optimal parenchymal function, such as pancreatic duct obstruction or impaired or poorly synchronized enzyme release. PURPOSE To provide practical guidance for primary care physicians managing patients who are at risk of PEI or who present with symptoms of PEI. METHODS For each of six key clinical questions identified by the authors, PubMed searches were conducted to identify key English-language papers up to April 2017. Forward and backward searches on key articles were conducted using Web of Science. Clinical recommendations proposed by the co-chairs (P.D. and C.T.) were vetted and approved based on the authors? FINDINGS The most characteristic symptom of PEI is steatorrhea ? voluminous, lipid-rich stools; other common signs and symptoms include unexplained weight loss and deficiencies of fat-soluble vitamins and other micronutrients. Pancreatic enzyme replacement therapy (PERT) can relieve symptoms and long-term sequelae of PEI. Diagnosis of PEI and initiation of PERT are usually the responsibility of gastroenterology specialists. However, primary care physicians (PCPs) are well positioned to identify potential cases of PEI and to participate in the collaborative, long-term management of patients already seen by a specialist. CONCLUSIONS In this document, a panel of Canadian gastroenterologists has conducted a critical review of the literature on PEI and PERT and has developed practical diagnostic and treatment recommendations for PCPs. These recommendations provide guidance on identifying patients at risk of PEI, the triggers for PEI testing and referral, and best practices for co-managing patients with confirmed PEI.
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Affiliation(s)
- P Durie
- a Hospital for Sick Children and University of Toronto , Toronto , ON , Canada
| | - J-D Baillargeon
- b Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke , Sherbrooke , QC , Canada
| | - S Bouchard
- c Centre Hospitalier de l'Université de Montréal , Montréal , QC , Canada
| | - F Donnellan
- d Vancouver General Hospital , Vancouver , BC , Canada
| | | | - C Teshima
- f St. Michael's Hospital and University of Toronto , Toronto , ON , Canada
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Bandsma R, Bozic M, Fridell J, Crull M, Molleston J, Avitzur Y, Mozer-Glassberg Y, Gonzalez-Peralta R, Hodik M, Fecteau A, de Angelis M, Durie P, Ng V. Simultaneous liver–pancreas transplantation for cystic fibrosis-related liver disease: A multicenter experience. J Cyst Fibros 2014; 13:471-7. [DOI: 10.1016/j.jcf.2013.12.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 12/03/2013] [Accepted: 12/30/2013] [Indexed: 10/25/2022]
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Rowland M, Gallagher C, Gallagher C, Olaoide R, Canny G, Broderick A, Greally P, Slattery D, Daly L, McElvaney N, Durie P, Bourke B. WS1.1 Liver disease in cystic fibrosis. J Cyst Fibros 2012. [DOI: 10.1016/s1569-1993(12)00085-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Gonska T, Keenan K, Dorfman R, Taylor C, Sun L, Ooi C, Ooi C, Zielenski J, Corey M, Rommens J, Strug L, Durie P. 12* The relation between meconium ileus prevalence score and functional severity of CFTR mutations. J Cyst Fibros 2011. [DOI: 10.1016/s1569-1993(11)60034-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Li W, Sun L, Corey M, Zou F, Lee S, Cojocaru AL, Taylor C, Blackman SM, Stephenson A, Sandford AJ, Dorfman R, Drumm ML, Cutting GR, Knowles MR, Durie P, Wright FA, Strug LJ. Understanding the population structure of North American patients with cystic fibrosis. Clin Genet 2011; 79:136-46. [PMID: 20681990 DOI: 10.1111/j.1399-0004.2010.01502.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
It is generally presumed that the cystic fibrosis (CF) population is relatively homogeneous, and predominantly of European origin. The complex ethnic make-up observed in the CF patients collected by the North American CF Modifier Gene Consortium has brought this assumption into question, and suggested the potential for population substructure in the three CF study samples collected from North America. It is well appreciated that population substructure can result in spurious genetic associations. To understand the ethnic composition of the North American CF population, and to assess the need for population structure adjustment in genetic association studies with North American CF patients, genome-wide single-nucleotide polymorphisms on 3076 unrelated North American CF patients were used to perform population structure analyses. We compared self-reported ethnicity to genotype-inferred ancestry, and also examined whether geographic distribution and cystic fibrosis transmembrane regulator (CFTR) mutation type could explain the population structure observed. Although largely Caucasian, our analyses identified a considerable number of CF patients with admixed African-Caucasian, Mexican-Caucasian and Indian-Caucasian ancestries. Population substructure was present and comparable across the three studies of the consortium. Neither geographic distribution nor CFTR mutation type explained the population structure. Given the ethnic diversity of the North American CF population, it is essential to carefully detect, estimate and adjust for population substructure to guard against potential spurious findings in CF genetic association studies. Other Mendelian diseases that are presumed to predominantly affect single ethnic groups may also benefit from careful analysis of population structure.
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Affiliation(s)
- W Li
- Child Health Evaluative Sciences Program, Hospital for Sick Children, Toronto, M5G 1X8, ON, Canada
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Gonska T, Ip W, Turner D, Han WS, Rose J, Durie P, Quinton P. Sweat gland bioelectrics differ in cystic fibrosis: a new concept for potential diagnosis and assessment of CFTR function in cystic fibrosis. Thorax 2009; 64:932-8. [DOI: 10.1136/thx.2009.115295] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Dorfman R, Nalpathamkalam T, Taylor C, Gonska T, Keenan K, Yuan XW, Corey M, Tsui LC, Zielenski J, Durie P. Do common in silico tools predict the clinical consequences of amino-acid substitutions in the CFTR gene? Clin Genet 2009; 77:464-73. [PMID: 20059485 DOI: 10.1111/j.1399-0004.2009.01351.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Computational methods are used to predict the molecular consequences of amino-acid substitutions on the basis of evolutionary conservation or protein structure, but their utility in clinical diagnosis or prediction of disease outcome has not been well validated. We evaluated three popular computer programs, namely, PANTHER, SIFT and PolyPhen, by comparing the predicted clinical outcomes for a group of known CFTR missense mutations against the diagnosis of cystic fibrosis (CF) and clinical manifestations in cohorts of subjects with CF-disease and CFTR-related disorders carrying these mutations. Owing to poor specificity, none of tools reliably distinguished between individual mutations that confer CF disease from mutations found in subjects with a CFTR-related disorder or no disease. Prediction scores for CFTR mutations derived from PANTHER showed a significant overall statistical correlation with the spectrum of disease severity associated with mutations in the CFTR gene. In contrast, PolyPhen- and SIFT-derived scores only showed significant differences between CF-causing and non-CF variants. Current computational methods are not recommended for establishing or excluding a CF diagnosis, notably as a newborn screening strategy or in patients with equivocal test results.
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Affiliation(s)
- R Dorfman
- Genetics and Genome Biology, Hospital for Sick Children, Toronto, Canada
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Schwarz M, Castellani C, Cuppens H, Macek M, Cassiman J, Kerem E, Durie P, Tullis E, Assael B, Bombieri C, Brown A, Casals T, Claustres M, Cutting G, Dodge J, Doull I, Farrell P, Ferec C, Girodon E, Johannesson M, Kerem B, Knowles M, Munck A, Pignatti P, Radojkovic D, Rizzotti P, Stuhrman M, Tzetis M, Zielenski J, Elborn J. EUROPEAN CYSTIC FIBROSIS SOCIETY CONSENSUS ON GENETIC TESTING. J Cyst Fibros 2008. [DOI: 10.1016/s1569-1993(08)60496-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Dorfman R, Nalpathamkalam T, Taylor C, Gonska T, Yuan X, Huang Q, Lin F, Jiang B, Corey M, Tsui L, Durie P, Zielenski J. Do in silico tools predict the clinical consequences of CFTR missense mutations? J Cyst Fibros 2008. [DOI: 10.1016/s1569-1993(08)60014-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Gonska T, Ip W, Bear C, Durie P, Quintan P. β-adrenergic stimulation alters sweat gland potential difference in cystic fibrosis (CF) patients but not healthy controls. J Cyst Fibros 2008. [DOI: 10.1016/s1569-1993(08)60091-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Dorfman R, Sandford A, Taylor C, Huang B, Frangolias D, Wong Y, Sun L, Pare P, Tsui L, Durie P, Corey M, Zielenski J. 12* Modulatory effect of MBL2 on the onset of Pseudomonas aeruginosa infection is influenced by the TGFβ1 variants in pediatric CF patients. J Cyst Fibros 2007. [DOI: 10.1016/s1569-1993(07)60012-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Taylor C, Corey M, Zielenski J, Breaton J, Rousseau R, VanSpall M, Christofi M, Frangolias D, Dorfman R, Sang R, Sandford A, Pare P, Durie P. Phenotype Definition for the Analysis of Modifier Genes in Cystic Fibrosis. Am J Epidemiol 2006. [DOI: 10.1093/aje/163.suppl_11.s128-d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Bhattacharjee R, Schibli S, Rose J, Tulhs E, Durie P, Ellis L, Kovesi T, Corey M. 260 The natural history of liver disease in Cystic Fibrosis. J Cyst Fibros 2006. [DOI: 10.1016/s1569-1993(06)80237-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Mei-Zahav M, Durie P, Zielenski J, Solomon M, Tullis E, Tsui LC, Corey M. The prevalence and clinical characteristics of cystic fibrosis in South Asian Canadian immigrants. Arch Dis Child 2005; 90:675-9. [PMID: 15970608 PMCID: PMC1720469 DOI: 10.1136/adc.2003.042614] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Cystic fibrosis (CF) is considered to be rare among individuals from the Indian subcontinent. Furthermore, affected individuals are reported to experience a more severe clinical course. AIMS It was hypothesised that CF is under diagnosed in people of South Asian origin and therefore the prevalence may be higher than previously estimated. METHODS The prevalence of CF in the South Asian and in the general population living in the same geographic region (Metropolitan Toronto) were compared between 1996 and 2001. Population data were obtained from the Canadian census survey. CF phenotype and genotype data were obtained from the Toronto CF database. RESULTS Among 381 patients with CF, 15 were of South Asian descent. The age related prevalence of CF among the South Asian and general populations was: 0-14 years, 1:9200 versus 1:6600; 15-24 years, 1:13,200 versus 1:7600; older than 25 years, 1:56,600 versus 1:12,400. Age at diagnosis, duration and severity of symptoms at diagnosis, current nutritional status, and FEV(1) were similar in the two groups. While not significant, FEV1 tended to be lower (48% versus 57% predicted) among adult South Asians, compared to the general CF population. Also, the percentage with pancreatic sufficiency was higher (27% versus 16%) and the frequency of DeltaF508 allele was lower (50% versus 65.1%). CONCLUSIONS These data suggest that the prevalence and natural history of CF in South Asians is similar to that among individuals of European origin. The relatively lower prevalence among older South Asians may reflect an improving recognition of CF in this ethnic subgroup.
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Affiliation(s)
- M Mei-Zahav
- Division of Respiratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
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15
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Ahmed N, Corey M, Forstner G, Zielenski J, Tsui LC, Ellis L, Tullis E, Durie P. Molecular consequences of cystic fibrosis transmembrane regulator (CFTR) gene mutations in the exocrine pancreas. Gut 2003; 52:1159-64. [PMID: 12865275 PMCID: PMC1773762 DOI: 10.1136/gut.52.8.1159] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
BACKGROUND AND AIMS We tested the hypothesis that the actual or predicted consequences of mutations in the cystic fibrosis transmembrane regulator gene correlate with the pancreatic phenotype and with measures of quantitative exocrine pancreatic function. METHODS We assessed 742 patients with cystic fibrosis for whom genotype and clinical data were available. At diagnosis, 610 were pancreatic insufficient, 110 were pancreatic sufficient, and 22 pancreatic sufficient patients progressed to pancreatic insufficiency after diagnosis. RESULTS We identified mutations on both alleles in 633 patients (85.3%), on one allele in 95 (12.8%), and on neither allele in 14 (1.9%). Seventy six different mutations were identified. The most common mutation was DeltaF508 (71.3%) followed by G551D (2.9%), G542X (2.3%), 621+1G-->T (1.2%), and W1282X (1.2%). Patients were categorized into five classes according to the predicted functional consequences of each mutation. Over 95% of patients with severe class I, II, and III mutations were pancreatic insufficient or progressed to pancreatic insufficiency. In contrast, patients with mild class IV and V mutations were consistently pancreatic sufficient. In all but four cases each genotype correlated exclusively with the pancreatic phenotype. Quantitative data of acinar and ductular secretion were available in 93 patients. Patients with mutations belonging to classes I, II, and III had greatly reduced acinar and ductular function compared with those with class IV or V mutations. CONCLUSION The predicted or known functional consequences of specific mutant alleles correlate with the severity of pancreatic disease in cystic fibrosis.
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Affiliation(s)
- N Ahmed
- Division of Gastroenterology and Nutrition, The Hospital for Sick Children, Toronto, Canada
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16
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Abstract
Growth failure is a common presentation of patients with pancreatic insufficient cystic fibrosis. However, full blown kwashiorkor is extremely rare. Cystic fibrosis is also considered to be rare in the South Asian population. This report describes a Sri Lankan infant with cystic fibrosis who presented with clinical features of severe kwashiorkor.
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Affiliation(s)
- M Mei-Zahav
- Division of Respiratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
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Whitcomb DC, Ulrich CD, Lerch MM, Durie P, Neoptolemos JP, Maisonneuve P, Lowenfels AB. Third International Symposium on Inherited Diseases of the Pancreas. Pancreatology 2002; 1:423-31. [PMID: 12120219 DOI: 10.1159/000055842] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- D C Whitcomb
- Departments of Medicine, Cell Biology and Physiology, and Human Genetics, University of Pittsburgh, 571 Scaife Hall, 3550 Terrace Street, Pittsburgh, PA 15261, USA.
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Affiliation(s)
- S L Katz
- Department of Pediatrics, Research Institute, the Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8
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Abstract
Shwachman-Diamond syndrome (SDS) is an inherited multisystem disorder characterized by exocrine pancreatic dysfunction and varying degrees of cytopenia. In addition, various immunological abnormalities have been noted. To clarify the issue of immunological competence or incompetence in SDS, we prospectively studied immune function in 11 patients with SDS. Seven suffered from recurrent bacterial infections and six from recurrent viral infections. Varying degrees of impairment were readily identified. All patients had neutropenia; total lymphocyte counts, however, were normal in all except one patient. Nine patients had B-cell defects comprising one or more of the following abnormalities: low IgG or IgG subclasses, low percentage of circulating B lymphocytes, decreased in vitro B-lymphocyte proliferation and a lack of specific antibody production. Seven out of nine patients studied had at least one T-cell abnormality comprising a low percentage of total circulating T lymphocytes or CD3+/CD4+ cell subpopulations or decreased in vitro T-lymphocyte proliferation. Five out of six patients studied had decreased percentages of circulating natural killer cells. Moreover, neutrophil chemotaxis was significantly low in all the patients studied. These data point to a major immunodeficiency component in SDS that places patients at heightened risk of infections, even if neutrophil numbers are protective. This finding broadens the definition of the syndrome substantially: it suggests that the SDS marrow defect occurs at the level of an early haematological-lymphocytic stem cell or that a combined marrow and thymic stromal defect accounts for the aberrant function of haematopoietic and lymphopoietic lineages.
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Affiliation(s)
- Y Dror
- Division of Haematology and Oncology, The Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada.
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Bhatia E, Durie P, Zielenski J, Lam D, Sikora SS, Choudhuri G, Tsui LC. Mutations in the cystic fibrosis transmembrane regulator gene in patients with tropical calcific pancreatitis. Am J Gastroenterol 2000; 95:3658-9. [PMID: 11151920 DOI: 10.1111/j.1572-0241.2000.03400.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Mak V, Zielenski J, Tsui LC, Durie P, Zini A, Martin S, Longley TB, Jarvi KA. Cystic fibrosis gene mutations and infertile men with primary testicular failure. Hum Reprod 2000; 15:436-9. [PMID: 10655318 DOI: 10.1093/humrep/15.2.436] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
It has been proposed that the gene responsible for cystic fibrosis, called the cystic fibrosis transmembrane conductance regulator (CFTR) gene, may play an important role in the process of spermatogenesis. A group of azoospermic men with primary testicular failure underwent CFTR mutation analysis, including assessment of the intron 8 polythymidine tract (IVS8-T tract). An association was not found between CFTR mutations or the 5T variant of the IVS8-T tract and the primary testicular failure phenotype. This finding suggests that CFTR does not play a significant role in the aetiopathogenesis of primary spermatogenic dysfunction. Therefore, the abnormal testicular histological findings in some post-pubertal men with cystic fibrosis may be a result of nutritional deficiency or testicular obstruction rather than a primary defect in spermatogenesis. In addition, the decreased sperm count in oligozoospermic men with CFTR mutations may be secondary to partial reproductive tract obstruction and not abnormal spermatogenesis. Lastly, routine screening of men with primary testicular failure for CFTR gene mutations is not warranted.
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Affiliation(s)
- V Mak
- Department of Surgery, Mount Sinai Hospital, Toronto, Ontario, Canada
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Abstract
BACKGROUND Patients with cystic fibrosis (CF) are at risk of developing vitamin K deficiency because of pancreatic insufficiency, hepatobiliary disease, or both. OBJECTIVE Our objective was to determine the prevalence of vitamin K deficiency in unsupplemented patients with CF and to identify risk factors that might be associated with the deficiency. DESIGN Ninety-eight patients with CF-83 who were pancreatic insufficient (age: 15.2 +/- 10.7 y; range: 0.6-45.8 y), 15 who were pancreatic sufficient (age: 26.2 +/- 11.6 y; range: 6.5-45.3 y), and 62 healthy individuals (age: 16.2 +/- 12. 8 y; range: 1-45 y)-were studied prospectively. None had taken vitamin K supplements. Eight pancreatic-insufficient patients had advanced CF-associated liver disease. Plasma prothrombin in vitamin K absence (PIVKA-II) was measured by immunoassay. All control subjects had PIVKA-II concentrations <3 microg/L. RESULTS Seventy-eight percent of pancreatic-insufficient patients had PIVKA-II concentrations >/=3 microg/L (22.8 +/- 35.7 microg/L). All patients with CF-associated liver disease had abnormal PIVKA-II concentrations. The mean PIVKA-II concentration of pancreatic-insufficient patients with liver disease was greater than that of those without liver disease (46.6 +/- 65.3 compared with 15. 3 +/- 26.1 microg/L; P < 0.05). Five pancreatic-sufficient patients had mildly elevated PIVKA-II concentrations. Six (7%) pancreatic insufficient patients (3 with CF-associated liver disease) had mildly prolonged prothrombin time but no clinical bleeding. There was no correlation between PIVKA-II concentrations and severity of fat malabsorption or antibiotic use. CONCLUSIONS Vitamin K deficiency is common in unsupplemented patients with CF and pancreatic insufficiency and routine supplementation should be considered in all of these patients.
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Affiliation(s)
- M Rashid
- Division of Gastroenterology and Nutrition, the Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
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Abstract
Patients with cystic fibrosis (CF) have abnormal concentrations and composition of electrolytes and macromolecules in gastrointestinal secretions. Such alterations could change intestinal surface properties, such as surface hydrophobicity, and may influence the adhesion of macromolecules, bacteria, or microbial toxins to the intestinal surface. The objective of this study was to compare the surface hydrophobicity of the gastrointestinal tract in wild type and CF mice. We used axisymmetric drop shape analysis-contact diameter to determine surface hydrophobicity by measuring contact angles of sessile water droplets placed onto epithelial surfaces. In wild type mice, there were no differences in contact angles between the duodenum, upper jejunum, lower jejunum, and ileum. The contact angle of the gastric mucosa was lower than the rest of the gastrointestinal tract. Contact angles of the proximal colon and distal colon were both higher than that of the gastric mucosa and those of the small intestinal sections. In CF mice, contact angles along the gastrointestinal tract followed the same pattern as in wild type mice. However, contact angles in the ileum and proximal colon of CF mice were greater than those from wild type mice. This study of the murine intestine showed regional differences in surface hydrophobicity comparable to those observed in other mammalian species. In addition, we showed that the ileum and proximal colon of CF mice were more hydrophobic than the corresponding segments in wild type mice. These observations are of potential clinical relevance because patients with CF exhibit clinical manifestations of gastrointestinal disease primarily in the ileum and proximal colon.
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Affiliation(s)
- C Chung
- The Research Institute, The Hospital for Sick Children, University of Toronto, Ontario, Canada
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Mak V, Zielenski J, Tsui LC, Durie P, Zini A, Martin S, Longley TB, Jarvi KA. Proportion of cystic fibrosis gene mutations not detected by routine testing in men with obstructive azoospermia. JAMA 1999; 281:2217-24. [PMID: 10376575 DOI: 10.1001/jama.281.23.2217] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT Infertile men with obstructive azoospermia may have mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, many of which are rare in classic cystic fibrosis and not evaluated in most routine mutation screening. OBJECTIVE To assess how often CFTR mutations or sequence alterations undetected by routine screening are detected with more extensive screening in obstructive azoospermia. DESIGN Routine screening for the 31 most common CFTR mutations associated with the CF phenotype in white populations, testing for the 5-thymidine variant of the polythymidine tract of intron 8 (IVS8-5T) by allele-specific oligonucleotide hybridization, and screening of all exons through multiplex heteroduplex shift analysis followed by direct DNA sequencing. SETTING Male infertility clinic of a Canadian university-affiliated hospital. SUBJECTS Of 198 men with obstructive (n = 149) or nonobstructive (n = 49; control group) azoospermia, 64 had congenital bilateral absence of the vas deferens (CBAVD), 10 had congenital unilateral absence of the vas deferens (CUAVD), and 75 had epididymal obstruction (56/75 were idiopathic). MAIN OUTCOME MEASURE Frequency of mutations found by routine and nonroutine tests in men with obstructive vs nonobstructive azoospermia. RESULTS Frequency of mutations and the IVS8-5T variant in the nonobstructive azoospermia group (controls) (2% and 5.1% allele frequency, respectively) did not differ significantly from that in the general population (2% and 5.2%, respectively). In the CBAVD group, 72 mutations were found by DNA sequencing and IVS8-5T testing (47 and 25, respectively; P<.001 and P = .002 vs controls) vs 39 by the routine panel (P<.001 vs controls). In the idiopathic epididymal obstruction group, 24 mutations were found by DNA sequencing and IVS8-5T testing (12 each; P=.01 and P=.14 vs controls) vs 5 by the routine panel (P=.33 vs controls). In the CUAVD group, 2 mutations were found by routine testing (P=.07 vs controls) vs 4 (2 each, respectively; P=.07 and P=.40 vs controls) by DNA sequencing and IVS8-5T testing. The routine panel did not identify 33 (46%) of 72, 2 (50%) of 4, and 19 (79%) of 24 detectable CFTR mutations and IVS8-5T in the CBAVD, CUAVD, and idiopathic epididymal obstruction groups, respectively. CONCLUSIONS Routine testing for CFTR mutations may miss mild or rare gene alterations. The barrier to conception for men with obstructive infertility has been overcome by assisted reproductive technologies, thus raising the concern of iatrogenically transmitting pathogenic CFTR mutations to the progeny.
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Affiliation(s)
- V Mak
- Department of Surgery, Mount Sinai Hospital, Toronto, Ontario, Canada
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Zielenski J, Corey M, Rozmahel R, Markiewicz D, Aznarez I, Casals T, Larriba S, Mercier B, Cutting GR, Krebsova A, Macek M, Langfelder-Schwind E, Marshall BC, DeCelie-Germana J, Claustres M, Palacio A, Bal J, Nowakowska A, Ferec C, Estivill X, Durie P, Tsui LC. Detection of a cystic fibrosis modifier locus for meconium ileus on human chromosome 19q13. Nat Genet 1999; 22:128-9. [PMID: 10369249 DOI: 10.1038/9635] [Citation(s) in RCA: 164] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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26
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Affiliation(s)
- R Shaoul
- The Hospital for Sick Children, Department of Pediatrics, University of Toronto, Ontario, Canada
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27
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Jarvi K, McCallum S, Zielenski J, Durie P, Tullis E, Wilchanski M, Margolis M, Asch M, Ginzburg B, Martin S, Buckspan MB, Tsui LC. Heterogeneity of reproductive tract abnormalities in men with absence of the vas deferens: role of cystic fibrosis transmembrane conductance regulator gene mutations. Fertil Steril 1998; 70:724-8. [PMID: 9797105 DOI: 10.1016/s0015-0282(98)00247-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
OBJECTIVE To determine if the types of reproductive tract abnormalities linked to absence of the vas deferens varies with the cystic fibrosis transmembrane conductance regulator (CFTR) genotype. DESIGN Prospective data gathering. SETTING University infertility clinic. PATIENT(S) Forty-six infertile men with absence of the scrotal vas deferens and no signs of cystic fibrosis. INTERVENTION(S) All had blood taken for CFTR gene analysis, 33 had scrotal ultrasounds, and 25 had transrectal ultrasounds. MAIN OUTCOME MEASURE(S) The frequency of testicular, seminal vesicle, and ampullae of the vas deferens malformations was compared between subgroups of men with two, one, or no CFTR gene mutations. RESULT(S) None (0 of 21) of the men with at least one CFTR gene mutations had normal ampullae of the vas or seminal vesicles bilaterally. Two (50%) of 4 men with no CFTR gene mutations had normal ampullae of the vas deferens bilaterally, and 50% had normal bilateral seminal vesicles (statistically significantly different). There was no correlation between testicular malformations and CFTR genotype. CONCLUSION(S) This study indicates that the severity of the malformations in the testis is unrelated to the CFTR genotype, whereas the frequency and severity of wolffian duct malformations are related directly to the CFTR genotype.
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Affiliation(s)
- K Jarvi
- Department of Surgery, Mount Sinai Hospital, Toronto, Ontario, Canada
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28
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Abstract
Shwachman-Diamond syndrome is an autosomal recessive disorder characterized by exocrine pancreatic dysfunction, bony metaphyseal dysostosis, various degrees of cytopenia, and a striking tendency to develop myelodysplastic syndrome and acute myeloblastic leukemia. Isochromosome 7 [i(7q)] is a rare non-random cytogenetic abnormality of myeloid cells in hematological malignancy. We report two cases of Shwachman-Diamond syndrome in which patients developed myelodysplastic syndrome and i(7q), detected by G-banding karyotype analysis and fluorescence in situ hybridization. Three other children have been previously reported to have myelodysplastic syndrome in association with i(7q); two of them had Shwachman-Diamond syndrome. Isochromosome 7q may be a fairly specific marker of myeloid malignant transformation in this syndrome and play a role in its pathogenesis.
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Affiliation(s)
- Y Dror
- Department of Paediatrics, The Hospital for Sick Children and University of Toronto, Ontario, Canada
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29
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Otulakowski G, Flueckiger-Staub S, Ellis L, Ramlall K, Staub O, Smith D, Durie P, O'Brodovich H. Relation between alpha, beta, and gamma human amiloride- sensitive epithelial Na+ channel mRNA levels and nasal epithelial potential difference in healthy men. Am J Respir Crit Care Med 1998; 158:1213-20. [PMID: 9769284 DOI: 10.1164/ajrccm.158.4.9710069] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
To analyze messenger RNA (mRNA) levels for the alpha, beta, and gamma subunits of the human amiloride-sensitive epithelial Na+ channel (hENaC) in respiratory epithelia, we developed a competitive quantitative reverse transcriptase-polymerase chain reaction (QRT-PCR) assay specific for each subunit, using two human respiratory epithelial-cell lines. We next determined the relation between hENaC mRNA levels and the biologic activity of the hENaC in the respiratory epithelium of eight normal men. The electrical potential difference (PD) between the epithelium of the inferior nasal turbinate and the subcutaneous space was measured, using control and amiloride (100 microM) solutions. QRT-PCR measurement of hENaC-subunit mRNAs and epithelial-specific cytokeratin 18 mRNA allowed us to normalize hENaC expression to epithelial-cell RNA. Respective values for alpha, beta, and gamma hENaC mRNA levels in epithelium obtained at the site of maximal PD were 39 +/- 4.0, 7.5 +/- 0.92, and 1.8 +/- 0.25 attomol/fmol cytokeratin mRNA, respectively. Respiratory epithelial PD exhibited a significant negative correlation with gamma hENaC (r2 = 0.72, p < 0.01), tended to increase with increasing alpha hENaC, and was unaffected by beta hENaC mRNA levels. Our results suggest that hENaC activity in vivo is influenced by expression of the gene for gamma hENaC. The assay used in the study provides a useful tool for evaluating Na+-channel expression in clinically relevant patient populations.
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Affiliation(s)
- G Otulakowski
- Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada.
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30
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Dror Y, Durie P, Marcon P, Freedman MH. Duplication of distal thumb phalanx in Shwachman-Diamond syndrome. Am J Med Genet 1998; 78:67-9. [PMID: 9637427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Shwachman-Diamond syndrome (SDS) comprises of exocrine pancreatic dysfunction, various degree of pancytopenia, and metaphyseal dysplasia. We report on a child with SDS and duplication of distal thumb phalanx. This combination has not been reported previously. We suggest that supernumerary thumb is likely a rare skeletal manifestation of SDS and that SDS should be considered in the differential diagnosis of patients with bone marrow failure and duplication of the thumb along with Blackfan-Diamond/Aase syndrome and Fanconi's anemia.
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Affiliation(s)
- Y Dror
- Division of Hematology and Oncology, The Hospital for Sick Children and the University of Toronto, Ontario, Canada
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31
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Ramjeesingh M, Huan LJ, Wilschanski M, Durie P, Li C, Gyomorey K, Wang Y, Kent G, Tanswell KA, Cutz E, Ackerley C, Bear CE. Assessment of the efficacy of in vivo CFTR protein replacement therapy in CF mice. Hum Gene Ther 1998; 9:521-8. [PMID: 9525313 DOI: 10.1089/hum.1998.9.4-521] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Cystic Fibrosis (CF) is caused by mutations in the CF gene that lead, for the most part, to mislocalization of the protein product, the cystic fibrosis transmembrane conductance regulatory (CFTR). CFTR is a chloride channel normally situated in the apical membrane of epithelial cells where it contributes to transepithelial ion transport. In this study we demonstrated the feasibility of in vivo transfer of purified CFTR protein via phospholipid liposomes into the apical membrane of nasal epithelia of CFTR knockout mice. Membrane incorporation of immunogold-labeled CFTR could be visualized by electron microscopy and correction of CF-related defects in ion transport measured by nasal potential difference (PD) measurements in about one-third of the animals treated. Although these initial results are promising, effectiveness of this therapeutic approach appears to be limited by the inefficient incorporation of CFTR into the apical epithelial cell membrane.
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Affiliation(s)
- M Ramjeesingh
- Division of Cell Biology, Research Institute at the Hospital for Sick Children, Toronto, Canada
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32
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Ellis L, Kalnins D, Corey M, Brennan J, Pencharz P, Durie P. Do infants with cystic fibrosis need a protein hydrolysate formula? A prospective, randomized, comparative study. J Pediatr 1998; 132:270-6. [PMID: 9506640 DOI: 10.1016/s0022-3476(98)70444-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVES We compared the nutritional benefits of a protein hydrolysate and a conventional infant formula in infants newly diagnosed with cystic fibrosis (CF). STUDY DESIGN Twenty-three infants with CF (<6 months of age) and pancreatic insufficiency were randomized to receive a hydrolysate formula (Alimentum) or a cow's milk-based formula (Similac). Each patient was monitored at 1 month and then every 3 months for 1 year. RESULTS Eighteen patients (8 Alimentum, 10 Similac) completed the study. At entry, the age distribution and clinical characteristics of each group were comparable. Energy intake with each formula was the same at 1 and 3 months, but at 6 and 12 months the hydrolysate-fed infants had higher age-adjusted energy intake. There were no differences in fecal energy or fecal fat at entry or throughout the study. Although the hydrolysate-fed infants were slightly more malnourished at diagnosis, growth velocity and nutritional status of infants with CF in each group were the same throughout the study. CONCLUSIONS The results of this randomized study fail to support the use of a hydrolyzed formula for the routine care of infants newly diagnosed with CF.
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Affiliation(s)
- L Ellis
- Research Institute and the Department of Nutrition, The Hospital for Sick Children, Toronto, Ontario, Canada
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33
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Affiliation(s)
- P Durie
- Department of Gastroenterology and Nutrition, Hospital for Sick Children, Toronto, Ontario, Canada
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34
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Mak V, Jarvi KA, Zielenski J, Durie P, Tsui LC. Higher proportion of intact exon 9 CFTR mRNA in nasal epithelium compared with vas deferens. Hum Mol Genet 1997; 6:2099-107. [PMID: 9328474 DOI: 10.1093/hmg/6.12.2099] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The 5-thymidine (5T) variant of the cystic fibrosis transmembrane conductance regulator (CFTR) intron 8 polypyrimidine tract (IVS8-T tract) is the most frequent CFTR gene alteration identified in men with congenital bilateral absence of vas deferens (CBAVD). This alternative splicing variant gives rise to two transcripts, one normal with exon 9 intact and the other with in-frame deletion of exon 9. That CBAVD men usually have none of the other clinical signs of classical cystic fibrosis (CF) suggests less functional CFTR is produced in the reproductive tract than in other CF-associated organs. Nasal epithelia and segments of vas deferens were obtained from healthy, previously vasectomized men who presented for vasectomy reversal. Quantitative RT-PCR was performed on these specimens, with the region of CFTR cDNA spanning exon 9 amplified. For both nasal and vasal tissues, a strong positive correlation was found between the length of the IVS8-T tract and the proportion of mRNA with exon 9 intact. In addition, within the same subject, a significantly higher level of transcripts lacking exon 9 was found in vas deferens than nasal epithelia, regardless of the IVS8-T genotype. These findings suggest that the splicing of CFTR precursor mRNA is less efficient in vasal epithelia compared with respiratory epithelia. Thus, differential splicing efficiency between the various tissues which express CFTR provides one possible explanation for the reproductive tract abnormalities observed in infertile men with CFTR gene alterations but without other clinical manifestations of CF.
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Affiliation(s)
- V Mak
- Division of Urology, Department of Surgery, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5, Canada
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35
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Rozmahel R, Gyömörey K, Plyte S, Nguyen V, Wilschanski M, Durie P, Bear CE, Tsui LC. Incomplete rescue of cystic fibrosis transmembrane conductance regulator deficient mice by the human CFTR cDNA. Hum Mol Genet 1997; 6:1153-62. [PMID: 9215687 DOI: 10.1093/hmg/6.7.1153] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We have used a mouse model to study the ability of human CFTR to correct the defect in mice deficient of the endogenous protein. In this model, expression of the endogenous Cftr gene was disrupted and replaced with a human CFTR cDNA by a gene targeted 'knock-in' event. Animals homozygous for the gene replacement failed to show neither improved intestinal pathology nor survival when compared to mice completely lacking CFTR. RNA analyses showed that the human CFTR sequence was transcribed from the targeted allele in the respiratory and intestinal epithelial cells. Furthermore, in vivo potential difference measurements showed that basal CFTR chloride channel activity was present in the apical membranes of both nasal and rectal epithelial cells in all homozygous knock-in animals examined. Ussing chamber studies showed, however, that the cAMP-mediated chloride channel function was impaired in the intestinal tract among the majority of homozygous knock-in animals. Hence, failure to correct the intestinal pathology associated with loss of endogenous CFTR was related to inefficient functional expression of the human protein in mice. These results emphasize the need to understand the tissue-specific expression and regulation of CFTR function when animal models are used in gene therapy studies.
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Affiliation(s)
- R Rozmahel
- Department of Genetics, The Hospital for Sick Children, Toronto, Ontario, Canada
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36
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Abstract
Fibrosing colonopathy, a recently described complication of patients with cystic fibrosis, manifests clinically approximately 7-12 months after starting high dose pancreatic enzyme treatment. Although the pathogenesis of fibrosing colonopathy is unknown, it is highly correlated with pancreatic enzyme dose. In this study, immune mediated factors which may be associated with fibrosing colonopathy were explored. Sera from 14 patients with cystic fibrosis and meconium ileus were collected at diagnosis and then longitudinally for four to five years after enzyme treatment. Sera were analysed for total IgG and antiporcine trypsin IgG using an ELISA assay. Before enzyme treatment, serum antiporcine trypsin IgG concentrations were negligible, at 2.9 (SD 0.3) micrograms/ml. Thirteen patients (93%) developed a significant antibody response to porcine trypsin after starting enzyme treatment, reaching a peak concentration of 69.4 (20.1) micrograms/ml 7-12 months after the introduction of enzymes. Since peak IgG concentrations coincided with published reports of time of onset of symptoms of fibrosing colonopathy, local injury by protease or by immune mediated mechanisms may be responsible for the pathological changes in this iatrogenic disease.
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Affiliation(s)
- J Lee
- Hospital for Sick Children, Department of Paediatrics, University of Toronto, Ontario, Canada
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37
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Abstract
Questions about the function of the disease-related gene are still not fully answered, but correlations are emerging between specific mutations and a patient's clinical condition. The strongest link is for pancreatic failure. A second involves azoospermia. Indeed, mutations are being found in males with infertility as the sole sign of disease. Improved knowledge of such patterns may suggest novel approaches to severe cystic fibrosis.
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Affiliation(s)
- L C Tsui
- Division of Gastroenterology and Nutrition, University of Toronto
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38
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Wilschanski M, Corey M, Durie P, Tullis E, Bain J, Asch M, Ginzburg B, Jarvi K, Buckspan M, Hartwick W. Diversity of reproductive tract abnormalities in men with cystic fibrosis. JAMA 1996; 276:607-8. [PMID: 8773631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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39
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Affiliation(s)
- M Greenwald
- Division of Rheumatology, Hospital for Sick Children, Toronto, Ontario, Canada
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40
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Kent G, Oliver M, Foskett JK, Frndova H, Durie P, Forstner J, Forstner GG, Riordan JR, Percy D, Buchwald M. Phenotypic abnormalities in long-term surviving cystic fibrosis mice. Pediatr Res 1996; 40:233-41. [PMID: 8827771 DOI: 10.1203/00006450-199608000-00008] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Mouse models for cystic fibrosis (CF) with no CFTR function (Cftr-/-) have the disadvantage that most animals die of intestinal obstruction shortly after weaning. The objective of this research was to extend the lifespan of CF mice and characterize their phenotype. Weanlings were placed on a nutrient liquid diet, and histologic and functional aspects of organs implicated in the disease were subsequently examined. Approximately 90% of Cftr-/- mice survived to 60 d, the majority beyond 100 d. Cftr-/- mice were underweight and had markedly abnormal intestinal histology. The intestinal epithelia did not respond to challenges with agents that raised intracellular cAMP, consistent with the absence of functional CFTR. No lesions or functional abnormalities were evident in the lungs. Liquid-fed Cftr-/- mice were infertile, although some males weaned to a solid diet were fertile before they died. Thus, we have succeeded in using dietary means to prolong the lives of Cftr-/- mice.
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Affiliation(s)
- G Kent
- Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
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41
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Rozmahel R, Wilschanski M, Matin A, Plyte S, Oliver M, Auerbach W, Moore A, Forstner J, Durie P, Nadeau J, Bear C, Tsui LC. Modulation of disease severity in cystic fibrosis transmembrane conductance regulator deficient mice by a secondary genetic factor. Nat Genet 1996; 12:280-7. [PMID: 8589719 DOI: 10.1038/ng0396-280] [Citation(s) in RCA: 311] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Mice that have been made deficient for the cystic fibrosis transmembrane conductance regulator (Cftr) usually die of intestinal obstruction. We have created Cftr-deficient mice and demonstrate prolonged survival among backcross and intercross progeny with different inbred strains, suggesting that modulation of disease severity is genetically determined. A genome scan showed that the major modifier locus maps near the centromere of mouse chromosome 7. Electrophysiological studies on mice with prolonged survival show that the partial rectification of Cl- and Na+ ion transport abnormalities can be explained in part by up-regulation of a calcium-activated Cl- conductance. Identification of modifier genes in our Cftr(m1HSC)/Cftr(m1HSC) mice should provide important insight into the heterogeneous disease presentation observed among CF patients.
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Affiliation(s)
- R Rozmahel
- Department of Molecular Genetics, The University of Toronto, Ontario, Canada
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Wilschanski MA, Rozmahel R, Beharry S, Kent G, Li C, Tsui LC, Durie P, Bear CE. In vivo measurements of ion transport in long-living CF mice. Biochem Biophys Res Commun 1996; 219:753-9. [PMID: 8645253 DOI: 10.1006/bbrc.1996.0306] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The Cftr (Cystic Fibrosis Transmembrane Conductance Regulator) gene codes for an epithelial chloride (C1) channel essential for fluid secretion into the respiratory and gastrointestinal tract and from exocrine glands. Mice lacking CFTR function due to a disruption of Cftr exon 10 or exon 1 (Cftr (m1UNC/m1UNC) or Cftr(m1HSC/m1HFC) mice, respectively) generally suffer from severe gastrointestinal disease resulting in death shortly after birth or at the time of weaning. However, a subgroup of the Cftr(m1HSC/m1HSC) mice have been characterized which exhibit relatively mild intestinal pathology resulting in a noncompromised lifespan compared to the more severely affected Cftr(m1UNC/m1UNC) mice. We compared the ion transport capacity of the intestinal mucosa of the mildly and severely affected CF mice using the in vivo technique of rectal potential difference (PD) measurement and found that the net calcium-activated chloride conductance toward the lumen was much greater in the rectum of mildly affected mice than in the severely affected mice. Hence, the milder phenotype may be related to the expression of a factor which enhances the net calcium-activated chloride conductance into the lumen of the intestinal tract.
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Jarvi K, Zielenski J, Wilschanski M, Durie P, Buckspan M, Tullis E, Markiewicz D, Tsui LC. Cystic fibrosis transmembrane conductance regulator and obstructive azoospermia. Lancet 1995; 345:1578. [PMID: 7540706 DOI: 10.1016/s0140-6736(95)91131-6] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Zielenski J, Markiewicz D, Chen HS, Schappert K, Seller A, Durie P, Corey M, Tsui LC. Identification of six mutations (R31L, 441delA, 681delC, 1461ins4, W1089R, E1104X) in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Hum Mutat 1995; 5:43-7. [PMID: 7537150 DOI: 10.1002/humu.1380050106] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Six new mutations have been identified in the CFTR gene. These mutations, representing three different categories--missense (R31L, W1098R), nonsense (E1104X), and frameshift (441delA, 681delC, 1461ins4)--are located in exons 2, 4, 5, 9, and 17b of the gene and presumed to cause cystic fibrosis (CF) in patients. All these mutations are probably rare in the population, as no additional examples were found for any of them in a cohort of 545 CF patients. Our study also revealed a benign sequence variation (3499 + 45T-->C) in intron 17b.
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Affiliation(s)
- J Zielenski
- Department of Genetics, Hospital for Sick Children, Toronto, Ontario, Canada
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45
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Affiliation(s)
- M Wilschanski
- Department of Pediatrics, Hospital for Sick Children, Toronto, Ontario, Canada
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46
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Abstract
STUDY OBJECTIVE The discovery of pancreatitis in two children with methylmalonic acidemia led us to review the experience with pancreatitis in a large number of patients with organic acidemias to determine whether pancreatitis is an important complication of these disorders. DESIGN Case series. SETTING Pediatric metabolism services at five tertiary care centers. PATIENTS Records of all patients with organic acidemias followed at the five institutions during the past 10 years were reviewed. Pancreatitis was recognized by symptoms and laboratory findings and confirmed by imaging studies, surgery, or autopsy. At three institutions all cases of pancreatitis in children younger than 10 years were reviewed. MEASUREMENTS AND RESULTS Nine children with pancreatitis (seven with acute and two with chronic cases) were identified among 108 children with branched-chain organic acidemias. They ranged in age from 13 months to 9 years. Five had methylmalonic acidemia, three had isovaleric acidemia, and one had maple syrup urine disease. There were three deaths; acute hemorrhagic pancreatitis occurred in two children, and chronic pancreatitis was found at autopsy in a third. All three patients with isovaleric acidemia and pancreatitis were identified after the occurrence of pancreatitis. The survey of pancreatitis at three institutions found 57 other patients (none with an inborn error) in addition to three patients with inborn errors included in this study. CONCLUSIONS Acute or chronic pancreatitis may complicate branched-chain organic acidemias and must be considered in the assessment of patients with these disorders who have acute clinical deterioration and vomiting, abdominal pain, encephalopathy or shock, or milder symptoms. Conversely, an inborn error of organic acid metabolism should be considered in children with pancreatitis of unknown origin.
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Affiliation(s)
- S G Kahler
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710
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47
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Hamosh A, King TM, Rosenstein BJ, Corey M, Levison H, Durie P, Tsui LC, McIntosh I, Keston M, Brock DJ. Cystic fibrosis patients bearing both the common missense mutation Gly----Asp at codon 551 and the delta F508 mutation are clinically indistinguishable from delta F508 homozygotes, except for decreased risk of meconium ileus. Am J Hum Genet 1992; 51:245-50. [PMID: 1379413 PMCID: PMC1682672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The glycine-to-aspartic acid missense mutation at codon 551 (G551D), which is within the first nucleotide-binding fold of the cystic fibrosis transmembrane conductance regulator (CFTR), is the third most common cystic fibrosis (CF) mutation, with a worldwide frequency of 3.1% among CF chromosomes. Regions with a high frequency correspond to areas with large populations of Celtic descent. To determine whether G551D confers a different phenotype than does delta F508, the most common CF mutation, we studied 79 compound heterozygotes for G551D/delta F508, from nine centers in Europe and North America. Each subject was matched, by age and sex, with a delta F508 homozygote from the same center. A retrospective cohort analysis was performed on the following outcome parameters: age at diagnosis, sweat chloride, meconium ileus at birth, height, weight, weight for height, FVC, FEV1, chest X-ray score, pseudomonas colonization, pancreatic sufficiency, and Shwachman clinical score. There was less meconium ileus among the G551D/delta F508 compound heterozygotes (relative risk 0.33; 95% confidence interval .13-.86), as well as a trend toward later age at diagnosis of pancreatic insufficiency. No statistically significant difference was found between the groups for any other parameter. These results suggest that the CF genotype can be a predictor of pancreatic and intestinal phenotype. Prenatal counseling for the two genotype groups should differ only with respect to probability of meconium ileus. Clinical outcome (after survival of meconium ileus) for G551D/delta F508 compound heterozygotes and delta F508 homozygotes is indistinguishable; therefore, prognostic counseling should not differ.
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Affiliation(s)
- A Hamosh
- Center for Medical Genetics, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, MD
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48
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Kristidis P, Bozon D, Corey M, Markiewicz D, Rommens J, Tsui LC, Durie P. Genetic determination of exocrine pancreatic function in cystic fibrosis. Am J Hum Genet 1992; 50:1178-84. [PMID: 1376016 PMCID: PMC1682557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
We showed elsewhere that the pancreatic function status of cystic fibrosis (CF) patients could be correlated to mutations in the CF transmembrane conductance regulator (CFTR) gene. Although the majority of CF mutations--including the most common, delta F508--strongly correlated with pancreatic insufficiency (PI), approximately 10% of the mutant alleles may confer pancreatic sufficiency (PS). To extend this observation, genomic DNA of 538 CF patients with well-documented pancreatic function status were analyzed for a series of known mutations in their CFTR genes. Only 20 of the 25 mutations tested were found in this population. They accounted for 84% of the CF chromosomes, with delta F508 being the most frequent (71%), and the other mutations accounted for less than 5% each. A total of 30 different, complete genotypes could be determined in 394 (73%) of the patients. The data showed that each genotype was associated only with PI or only with PS, but not with both. This result is thus consistent with the hypothesis that PI and PS in CF are predisposed by the genotype at the CFTR locus; the PS phenotype occurs in patients who have one or two mild CFTR mutations, such as R117H, R334W, R347P, A455E, and P574H, whereas the PI phenotype occurs in patients with two severe alleles, such as delta F508, delta I507, Q493X, G542X, R553X, W1282X, 621 + 1G----T, 1717-1G----A, 556delA, 3659delC, I148T, G480C, V520F, G551D, and R560T.
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Affiliation(s)
- P Kristidis
- Department of Genetics, Hospital for Sick Children, Toronto, Ontario Canada
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Eberhard A, Couper R, Durie P, Silverman E. Exocrine pancreatic function in children with systemic lupus erythematosus. J Rheumatol Suppl 1992; 19:964-7. [PMID: 1404136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We examined the incidence and spectrum of pancreatic disease in pediatric systemic lupus erythematosus (SLE). We measured serum immunoreactive cationic trypsinogen (IRT) in 185 samples obtained from 35 patients with SLE. Fifteen patients (43%) had elevated IRT levels on at least one occasion. Serum samples were obtained in 20 of 35 patients before start of treatment. Seven of these 20 patients (35%) had elevated IRT levels at diagnosis, which slowly returned to normal as their disease was controlled with treatment. A further 3 of these 20 patients in whom we had sera at diagnosis had elevated levels at some course during their illness. Of the remaining 15 patients in whom sera was not available at diagnosis, 5 patients had increased IRT levels on at least one occasion. We show that elevated IRT levels are common in pediatric SLE, but there was no apparent association with drugs such as prednisone and azathioprine. However, high levels of IRT at the time of diagnosis may be related to an underlying disease component such as vasculitis.
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Affiliation(s)
- A Eberhard
- Department of Pediatrics, Hospital for Sick Children, University of Toronto, ON, Canada
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Couper R, Lichtman S, Cleghorn G, del Castillo V, Durie P. Serum immunoglobulin G directed against porcine trypsin in pancreatic insufficient cystic fibrosis patients receiving pancreatic enzyme supplements. Pancreas 1991; 6:558-63. [PMID: 1946313 DOI: 10.1097/00006676-199109000-00009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cystic fibrosis (CF) patients frequently malabsorb nutrients because of pancreatic failure. Standard therapy entails oral administration of porcine pancreatic enzymes, with meals. Porcine enzymes contain in excess of 25 potentially antigenic proteins. To evaluate antigenicity of one of these (porcine trypsin), we developed ELISA techniques capable of measuring total immunoglobulin G (IgG) and IgG directed against porcine trypsin in patient sera. Cross-sectional evaluation of sera from 12 controls and 41 CF patients showed that IgG directed against porcine trypsin was detectable in 12/17 CF patients receiving porcine enzymes (50.6 +/- 56.0 ng/ml; range 0-154.0 ng/ml), while none was detected in controls or the 26 CF subjects not receiving enzymes. In the 17 CF patients receiving enzymes, porcine trypsin binding IgG contributed 0.85 +/- 0.83% of the total IgG pool. Levels of porcine trypsin binding did not correlate with total IgG. Longitudinal evaluation was then performed in 26 CF patients, before and after commencement of enzyme therapy. Prior to commencing therapy, porcine trypsin binding IgG was undetectable in sera from 24/26 patients. Within 4.2 years of commencing therapy, 25/26 patients (96%) developed porcine trypsin binding IgG. Thus, serum IgG responses to porcine trypsin appear to be common in CF patients receiving porcine enzymes and contribute considerably to total IgG levels. Other individual enzymes in porcine extracts are likely to elicit similar antigenic response.
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Affiliation(s)
- R Couper
- Department of Pediatrics, Hospital for Sick Children, Toronto, Ontario, Canada
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