Cystic Fibrosis Transmembrane Research Articles

Genotypes and Phenotypes in Cystic Fibrosis and Cystic Fibrosis Transmembrane Regulator–Related Disorders

Cystic fibrosis (CF) is characterized by remarkable variability in severity, rate of disease progression, and organ involvement. In spite of the considerable amount of data collected on the relationship between genotype and phenotype in CF, this is still a challenging matter of debate. Barriers to the interpretation of this connection are the large number of mutations in the CF transmembrane regulator (CFTR) gene, the difficulties in attributing several of them to a specific mode of dysfunction, and a limited number of the almost 2,000 mutations so far detected, which have been clinically annotated. In addition to that, the heterogeneity of clinical manifestations in individuals with the same CFTR genotypes indicates that disease severity is modulated by other genes and by environmental factors, of which the most relevant is possibly treatment in its aspects of appropriateness, early start in life, and adherence. The phenotype variability extends to conditions, named CFTR-related disorders, which are connected with CFTR dysfunction, but do not satisfy diagnostic criteria for CF. The current level of knowledge does not allow use of the CFTR genotype to predict individual outcome and cannot be used as an indicator of CF prognosis. This might change with the development of treatments targeting specific mutations and possibly capable of changing the natural history of the disease.

Cystic fibrosis transmembrane conductance regulator modulators: the end of the beginning.

Cystic fibrosis (CF) represents one of the success stories of modern medicine with sustained incremental increases in the survival from one of childhood death to one of adult survival into the middle decades over the past 30 years. Improving survival has focused on multidisciplinary management centered on treating the consequences of this genetic disease. It has been firmly established for more than 20 years that mutations in the CF transmembrane conductance regulator (CFTR) gene result in a defective protein that normally functions as a chloride channel on epithelial cell surfaces. Until recently, modulating CFTR dysfunction was only a research aspiration, however, greater focus placed upon addressing the primary defect of CF has developed several clinical therapeutic strategies in this area. This review highlights the evidence to date on efforts to modulate CFTR and restore robust functional protein to the cell surface. This approach has now led to the licensing of one CFTR potentiator, which has been shown to have significant clinical improvements in a subset of CF patients. This success represents the beginning for CFTR modulation and further research is ongoing which aims to broaden the applicability of these techniques.

Synthetic Aminoglycosides Efficiently Suppress Cystic Fibrosis Transmembrane Conductance Regulator Nonsense Mutations and Are Enhanced by Ivacaftor

New drugs are needed to enhance premature termination codon (PTC) suppression to treat the underlying cause of cystic fibrosis (CF) and other diseases caused by nonsense mutations. We tested new synthetic aminoglycoside derivatives expressly developed for PTC suppression in a series of complementary CF models. Using a dual-luciferase reporter system containing the four most prevalent CF transmembrane conductance regulator (CFTR) nonsense mutations (G542X, R553X, R1162X, and W1282X) within their local sequence contexts (the three codons on either side of the PTC), we found that NB124 promoted the most readthrough of G542X, R1162X, and W1282X PTCs. NB124 also restored full-length CFTR expression and chloride transport in Fischer rat thyroid cells stably transduced with a CFTR-G542XcDNA transgene, and was superior to gentamicin and other aminoglycosides tested. NB124 restored CFTR function to roughly 7% of wild-type activity in primary human bronchial epithelial (HBE) CF cells (G542X/delF508), a highly relevant preclinical model with endogenous CFTR expression. Efficacy was further enhanced by addition of the CFTR potentiator, ivacaftor (VX-770), to airway cells expressing CFTR PTCs. NB124 treatment rescued CFTR function in a CF mouse model expressing a human CFTR-G542X transgene; efficacy was superior to gentamicin and exhibited favorable pharmacokinetic properties, suggesting that in vitro results translated to clinical benefit in vivo. NB124 was also less cytotoxic than gentamicin in a tissue-based model for ototoxicity. These results provide evidence that NB124 and other synthetic aminoglycosides provide a 10-fold improvement in therapeutic index over gentamicin and other first-generation aminoglycosides, providing a promising treatment for a wide array of CFTR nonsense mutations.

Lung Phenotype of Juvenile and Adult Cystic Fibrosis Transmembrane Conductance Regulator–Knockout Ferrets

Chronic bacterial lung infections in cystic fibrosis (CF) are caused by defects in the CF transmembrane conductance regulator chloride channel. Previously, we described that newborn CF transmembrane conductance regulator-knockout ferrets rapidly develop lung infections within the first week of life. Here, we report a more slowly progressing lung bacterial colonization phenotype observed in juvenile to adult CF ferrets reared on a layered antibiotic regimen. Even on antibiotics, CF ferrets were still very susceptible to bacterial lung infection. The severity of lung histopathology ranged from mild to severe, and variably included mucus obstruction of the airways and submucosal glands, air trapping, atelectasis, bronchopneumonia, and interstitial pneumonia. In all CF lungs, significant numbers of bacteria were detected and impaired tracheal mucociliary clearance was observed. Although Streptococcus, Staphylococcus, and Enterococcus were observed most frequently in the lungs of CF animals, each animal displayed a predominant bacterial species that accounted for over 50% of the culturable bacteria, with no one bacterial taxon predominating in all animals. Matrix-assisted laser desorption-ionization time-of-flight mass spectrometry fingerprinting was used to quantify lung bacteria in 10 CF animals and demonstrated Streptococcus, Staphylococcus, Enterococcus, or Escherichia as the most abundant genera. Interestingly, there was significant overlap in the types of bacteria observed in the lung and intestine of a given CF animal, including bacterial taxa unique to the lung and gut of each CF animal analyzed. These findings demonstrate that CF ferrets develop lung disease during the juvenile and adult stages that is similar to patients with CF, and suggest that enteric bacterial flora may seed the lung of CF ferrets.

CFTR Gene Mutations and Asthma in Indian Children: A Case-Control Study.

Cystic Fibrosis Trans membrane conductance regulator (CFTR) gene is an asthma susceptibility gene. In the present study we investigated the possible association of CFTR gene mutations in Indian asthmatic children as compared to controls. The study included 250 asthmatics and 250 age and sex matched controls. Case to control ratio for sample size was 1:1. Genotyping was performed for 24 CFTR gene mutations by ARMS-PCR and PCR-RFLP method. Among 24 CFTR gene mutations, heterozygous allele of R553X mutation was found in 4 (1.6%) asthmatic cases and 2 (0.8%) controls. Value of FVC and FEV1/FVC ratio were significantly lower in heterozygous individuals (p value <0.05). No significant difference was observed in the genotype and allele frequency of R553X mutation (OR =1.339, 95 % CI = 0.755-2.374, p value = 0.685). Furthermore, all wild type homozygous alleles were observed in remaining 23 CFTR gene mutations. Our data concludes that R553X mutation was not significantly associated in Indian asthmatic children.

Proteome of the porosome complex in human airway epithelia: Interaction with the cystic fibrosis transmembrane conductance regulator (CFTR)

The surface of the airways is coated with a thin film of mucus composed primarily of mucin, which is under continuous motion via ciliary action. Mucin not only serves to lubricate the airways epithelia, but also functions as a trap for foreign particles and pathogens, thereby assisting in keeping the airways clean and free of particulate matter and infections. Altered mucin secretion especially increased mucin viscosity, results in mucin stagnation due to the inability of the cilia to propel them, leading to infections and diseases such as cystic fibrosis (CF). Since porosomes have been demonstrated to be the secretory portals at the cell plasma membrane in cells, their presence, structure, and composition in the mucin-secreting human airway epithelial cell line Calu-3 expressing CF transmembrane receptor (CFTR), were investigated. Atomic force microscopy (AFM) of Calu-3 cells demonstrates the presence of approximately 100nm in diameter porosome openings at the plasma membrane surface. Electron microscopy confirms the AFM results, and tandem mass spectrometry and immunoanalysis performed on isolated Calu-3 porosomes, reveal the association of CFTR with the porosome complex. These new findings will facilitate understanding of CFTR-porosome interactions influencing mucous secretion, and provide critical insights into the etiology of CF disease. In the present study, the porosome proteome in human airway epithelia has been determined. The interaction between the cystic fibrosis transmembrane conductance regulator (CFTR) and the porosome complex in the human airway epithelia is further demonstrated. The possible regulation by CFTR on the quality of mucus secretion via the porosome complex at the cell plasma membrane is hypothesized. These new findings will facilitate understanding of CFTR-porosome interactions influencing mucous secretion, and provide critical insights into the etiology of CF disease.

Correction of Chloride Transport and Mislocalization of CFTR Protein by Vardenafil in the Gastrointestinal Tract of Cystic Fibrosis Mice

Although lung disease is the major cause of mortality in cystic fibrosis (CF), gastrointestinal (GI) manifestations are the first hallmarks in 15–20% of affected newborns presenting with meconium ileus, and remain major causes of morbidity throughout life. We have previously shown that cGMP-dependent phosphodiesterase type 5 (PDE5) inhibitors rescue defective CF Transmembrane conductance Regulator (CFTR)-dependent chloride transport across the mouse CF nasal mucosa. Using F508del-CF mice, we examined the transrectal potential difference 1 hour after intraperitoneal injection of the PDE5 inhibitor vardenafil or saline to assess the amiloride-sensitive sodium transport and the chloride gradient and forskolin-dependent chloride transport across the GI tract. In the same conditions, we performed immunohistostaining studies in distal colon to investigate CFTR expression and localization. F508del-CF mice displayed increased sodium transport and reduced chloride transport compared to their wild-type littermates. Vardenafil, applied at a human therapeutic dose (0.14 mg/kg) used to treat erectile dysfunction, increased chloride transport in F508del-CF mice. No effect on sodium transport was detected. In crypt colonocytes of wild-type mice, the immunofluorescence CFTR signal was mostly detected in the apical cell compartment. In F508del-CF mice, a 25% reduced signal was observed, located mostly in the subapical region. Vardenafil increased the peak of intensity of the fluorescence CFTR signal in F508del-CF mice and displaced it towards the apical cell compartment. Our findings point out the intestinal mucosa as a valuable tissue to study CFTR transport function and localization and to evaluate efficacy of therapeutic strategies in CF. From our data we conclude that vardenafil mediates potentiation of the CFTR chloride channel and corrects mislocalization of the mutant protein. The study provides compelling support for targeting the cGMP signaling pathway in CF pharmacotherapy.

Cystic Fibrosis Transmembrane Regulator Correctors and Potentiators

Cystic fibrosis (CF) is caused by loss-of-function mutations in the CF transmembrane conductance regulator (CFTR) protein, a cAMP-regulated anion channel expressed primarily at the apical plasma membrane of secretory epithelia. Nearly 2000 mutations in the CFTR gene have been identified that cause disease by impairing its translation, cellular processing, and/or chloride channel gating. The fundamental premise of CFTR corrector and potentiator therapy for CF is that addressing the underlying defects in the cellular processing and chloride channel function of CF-causing mutant CFTR alleles will result in clinical benefit by addressing the basic defect underlying CF. Correctors are principally targeted at F508del cellular misprocessing, whereas potentiators are intended to restore cAMP-dependent chloride channel activity to mutant CFTRs at the cell surface. This article reviews the discovery of CFTR potentiators and correctors, what is known regarding their mechanistic basis, and encouraging results achieved in clinical testing.

Novel Amino-Carbonitrile-Pyrazole Identified in a Small Molecule Screen Activates Wild-Type and ∆F508 Cystic Fibrosis Transmembrane Conductance Regulator in the Absence of a cAMP Agonist

Cystic fibrosis (CF) is caused by loss-of-function mutations in the CF transmembrane conductance regulator (CFTR) Cl⁻ channel. We developed a phenotype-based high-throughput screen to identify small-molecule activators of human airway epithelial Ca²⁺-activated Cl⁻ channels (CaCCs) for CF therapy. Unexpectedly, screening of ∼110,000 synthetic small molecules revealed an amino-carbonitrile-pyrazole, C(act)-A1, that activated CFTR but not CaCC Cl⁻ conductance. C(act)-A1 produced large and sustained CFTR Cl⁻ currents in CFTR-expressing Fisher rat thyroid (FRT) cells and in primary cultures of human bronchial epithelial (HBE) cells, without increasing intracellular cAMP and in the absence of a cAMP agonist. C(act)-A1 produced linear whole-cell currents. C(act)-A1 also activated ΔF508-CFTR Cl⁻ currents in low temperature-rescued ΔF508-CFTR-expressing FRT cells and CF-HBE cells (from homozygous ΔF508 patients) in the absence of a cAMP agonist, and showed additive effects with forskolin. In contrast, N-(2,4-di-tert-butyl-5-hydroxyphenyl)-4-oxo-1,4-dihydroquinoline-3-carboxamide (VX-770) and genistein produced little or no ΔF508-CFTR Cl⁻ current in the absence of a cAMP agonist. In FRT cells expressing G551D-CFTR and in CF nasal polyp epithelial cells (from a heterozygous G551D/Y1092X-CFTR patient), C(act)-A1 produced little Cl⁻ current by itself but showed synergy with forskolin. The amino-carbonitrile-pyrazole C(act)-A1 identified here is unique among prior CFTR-activating compounds, as it strongly activated wild-type and ΔF508-CFTR in the absence of a cAMP agonist. Increasing ΔF508-CFTR Cl⁻ conductance by an "activator," as defined by activation in the absence of cAMP stimulation, provides a novel strategy for CF therapy that is different from that of a "potentiator," which requires cAMP elevation.

Cystic fibrosis and fertility

As the life expectancy of cystic fibrosis (CF) patients continues to increase, and more patients become adults with a chronic disease, researching the impact of the disorder on male and female infertility has become increasingly important. Studies suggest that the prevalence of CF mutations may be higher than previously thought and that many mutations are yet to be identified. Assisted reproductive technologies can help both infertile male and female patients with CF in achieving successful parenthood. In addition, for women more health characteristics including baseline pulmonary function have been evaluated as predictors of health and pregnancy outcomes. Mutations in the CF Transmembrane Conductance Regulator (CFTR) gene affect both male and female fertility; however, not all CFTR mutations appear to cause infertility. Although most men with CF have significant anatomical abnormalities of the reproductive tract causing infertility, most women with CF have anatomically normal reproductive tracts and up to half may be able to conceive spontaneously. Less is known about how CF affects female fertility or the treatment options available.

Impaired airway epithelial barrier function in cystic fibrosis related diabetes

Cystic Fibrosis (CF)‐Related Diabetes (CFRD) impacts ~50% of adult CF patients. CFRD is associated with abnormally high airway glucose and an accelerated decline in pulmonary function, indicating a failure in the airway epithelial barrier to regulate glucose permeability. Thus, we examined tight junctions of airway cells expressing wild type CF Transmembrane Conductance Regulator (CFTR) to cells expressing mutant ΔF508‐CFTR. Increasing basolateral glucose from 100 to 450 mg/dL compromised tight junctions of ΔF508‐CFTR cells by ~25% vs. control cells which were significantly less affected. Impaired barrier function was associated with decreased expression of claudin‐4 and displacement of junctional ZO‐1. Using a dual‐luciferase‐ based ER stress reporter assay, cells expressing ΔF508‐ CFTR exhibited higher levels of ER stress than control cells. ER stress was further induced upon exposure to high glucose medium. Thus, ER stress amplified by expression of ΔF508‐CFTR impairs the airway glucose barrier and may predispose the lungs of CF patients to the detrimental consequences of systemic diabetes. Support: Emory+Children's Center for CF Research, Emory URC, CFF, NIH‐NIAAA, NIH‐NHLBI.

Rescue of Dysfunctional Autophagy Attenuates Hyperinflammatory Responses from Cystic Fibrosis Cells

A hallmark feature of cystic fibrosis (CF) is progressive pulmonary obstruction arising from exaggerated host proinflammatory responses to chronic bacterial airway colonization. The mechanisms for these heightened inflammatory responses have been only partially characterized, hampering development of effective anti-inflammatory therapies. The aim of this study was to identify and validate novel dysfunctional processes or pathways driving the hyperinflammatory phenotype of CF cells using systems biology and network analysis to examine transcriptional changes induced by innate defense regulator (IDR)-1018, an anti-inflammatory peptide. IDR-1018 selectively attenuated hyperinflammatory cytokine production from CF airway cells and PBMCs stimulated with multiple bacterial ligands, including flagellin (FliC). Network analysis of CF cell transcriptional responses to FliC and IDR-1018 identified dysfunctional autophagy as the target of the peptide via modulation of upstream adenosine monophosphate-activated protein kinase (AMPK)-Akt signaling. After treatment with FliC, CF cells were found to have elevated levels of the autophagosome marker LC3-II, and GFP-LC3-transfected CF airway cells showed abnormal perinuclear accumulation of GFP(+) structures. In both instances, treatment of CF cells with IDR-1018 abolished the accumulation of LC3 induced by FliC. Furthermore, inhibition of autophagosome-lysosome fusion with bafilomycinA1 attenuated the anti-inflammatory and autophagosome-clearing effects of IDR-1018, as did a chemical inhibitor of Akt and an activator of AMPK. These findings were consistent with hypotheses generated in silico, demonstrating the utility of systems biology and network analysis approaches for providing pathway-level insights into CF-associated inflammation. Collectively, these data suggest that dysfunctional autophagosome clearance contributes to heightened inflammatory responses from CF transmembrane receptor mutant cells and highlight autophagy and AMPK-Akt signaling as novel anti-inflammatory targets in CF.

Role of Cystic Fibrosis Transmembrane Conductance Regulator in Patients With Chronic Sinopulmonary Disease

Previous studies report a high frequency of mutations in the cystic fibrosis (CF) transmembrane conductance regulator gene (CFTR) in patients with idiopathic bronchiectasis. However, most studies have based their findings on preselected patient groups or have performed limited testing for CF transmembrane conductance regulator (CFTR) dysfunction. The objective of our study was to evaluate the prevalence of CFTR gene mutations and/or CFTR-related ion channel abnormalities among subjects with idiopathic chronic sinopulmonary disease and the prevalence of CF or a CFTR-related disorder in this population. We evaluated 72 prospectively enrolled patients from 1995 to 2005 at the Hospital for Sick Children and St. Michael’s Hospital with idiopathic chronic sinopulmonary disease for evidence of CFTR-mediated abnormalities. We performed CFTR genotyping and assessed CFTR function using sweat testing and nasal potential difference testing. The results were compared with data from healthy control subjects, CF heterozygotes, and patients with CF. The CFTR functional tests in idiopathic sinopulmonary patients showed a continuous spectrum, ranging from normal to values typically seen in individuals with CF. Forty-eight patients (66%) demonstrated CFTR mutations and/or abnormalities of CFTR function. Twenty-two (31%) fulfilled criteria for a diagnosis of CF and 26 (36%) for a CFTR-related disorder with a strong female preponderance. Functional tests, more than genotyping, were instrumental in establishing a CF diagnosis. Clinical features failed to distinguish subjects with CF from those with CFTR-related or idiopathic disease. The high prevalence of CF and CFTR dysfunction among patients with idiopathic chronic sinopulmonary disease underscores the need for extensive diagnostic evaluation for CF.

A review of pathophysiology and management of fetuses and neonates with meconium ileus for the pediatric surgeon

PurposeMeconium ileus (MI) is the earliest clinical manifestation of cystic fibrosis (CF), occurring in up to 20% of patients with CF. Our aim was to review and integrate current knowledge about the diagnosis and management of fetuses and neonates with MI that may aid the pediatric surgeon in caring for these patients. MethodsWe identified areas of interest including pathophysiology, prenatal diagnosis, nonoperative and operative management, postoperative management, and prognosis. We performed a Medline search using the search term meconium ileus for English language articles published in the last 20 years. We reviewed reference lists to identify other articles of historical significance. ResultsMeconium ileus is primarily associated with CF transmembrane (conductance) regulator mutations F508del, G542X, W1282X, R553X, and G551D, and modifier genes have been found to explain approximately 17% of the phenotypic variability. Mouse, pig, and ferret models for CF demonstrate neonatal bowel obstruction mimicking MI. Sonographic findings of hyperechoic masses and dilated bowel in a high-risk fetus are suggestive of MI. Less than 7% of low-risk fetuses with hyperechoic bowel will have MI. Contemporary series of noninvasive management with Gastrografin enema report success rates of 36% to 39%, significantly lower than historical values. The optimal surgical technique remains controversial, although primary anastomosis results in surgical complication rates between 21% and 31%, higher than those noted with delayed anastomosis. Pulmonary function for patients with CF and MI at 15 and 25 years old is similar to those without MI, although height and weight percentiles may be lower. ConclusionsThis review for pediatric surgeons presents an examination of the literature and synthesizes current information about the pathophysiology, prenatal diagnosis, nonoperative and operative management, postoperative management, and prognosis of the patient with CF and MI.

Pharmacological Rescue of the Mutant Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Detected by Use of a Novel Fluorescence Platform

Numerous human diseases arise because of defects in protein folding, leading to their degradation in the endoplasmic reticulum. Among them is cystic fibrosis (CF), caused by mutations in the gene encoding the CF transmembrane conductance regulator (CFTR ), an epithelial anion channel. The most common mutation, F508del, disrupts CFTR folding, which blocks its trafficking to the plasma membrane. We developed a fluorescence detection platform using fluorogen-activating proteins (FAPs) to directly detect FAP-CFTR trafficking to the cell surface using a cell-impermeant probe. By using this approach, we determined the efficacy of new corrector compounds, both alone and in combination, to rescue F508del-CFTR to the plasma membrane. Combinations of correctors produced additive or synergistic effects, improving the density of mutant CFTR at the cell surface up to ninefold over a single-compound treatment. The results correlated closely with assays of stimulated anion transport performed in polarized human bronchial epithelia that endogenously express F508del-CFTR. These findings indicate that the FAP-tagged constructs faithfully report mutant CFTR correction activity and that this approach should be useful as a screening assay in diseases that impair protein trafficking to the cell surface.

Ivacaftor approved for cystic fibrosis

FDA on January 31 announced the approval of ivacaftor, an oral therapy that the agency called a breakthrough in personalized medicine for people with a rare form of cystic fibrosis (CF). Ivacaftor is sold as Kalydeco by Vertex Pharmaceuticals. Ivacaftor is a cystic fibrosis transmembrane

Finding new medicines to fight CF: multiple steps of a success story

Background Cystic fibrosis (CF) is a major life-limiting genetic disease leading to severe respiratory symptoms caused by mutations in CF trans membrane conductance regulator (CFTR), a chloride channel expressed at the apical membrane of epithelial cells. Absence of functional CFTR from the surface of respiratory cells reduces mucociliary clearance, promoting airways obstruction, chronic infection and ultimately lung failure [1]. Despite major clinical advances treating the symptoms, which pushed survival beyond the second decade (~25 years in Europe), CF is still a life-limiting condition [2]. However, to further increase CF patients life expectancy, CF needs to be treated beyond its symptoms, i.e., through treatments addressing the basic defect associated with CFTR gene mutations [3]. So far ~1,900 CFTR mutations were reported [4], but one single mutation, F508del remains the most common one, as it occurs in ~90% of CF patients in at least one allele [5] and is associated with a severe clinical phenotype. Despite that most of efforts are focused on correcting the F508del-CFTR which causes intracellular retention of the mutant channel at the endoplasmic reticulum (ER), several additional strategies are emerging to rescue other (rarer mutants) which, in some populations, also have high prevalence. To this end, CFTR mutations are usually grouped into functional classes, towards a “mutation-specific” therapeutic approach by which mutations within the same functional class can be corrected by the same therapeutic strategy towards a “personalized medicine” approach [6]. Materials and methods/ results To apply such strategy CFTR mutations are thus classified into six main functional categories [7,8], namely: i) class I mutations (often mutations generating premature stop codons, e.g., R1162X) prevent protein production; ii) class II mutations (includes F508del) cause intracellular retention and premature degradation, thus preventing mutant CFTR from reaching the cell surface; iii) class III mutants (e.g., G551D) cause impairment in the channel gating (i.e., decreased open probability); iv) class IV mutants have substantially reduced flow of Cl ions through the CFTR channel (e.g., R334W); v) class V mutants include mostly alternative splicing mutants (e.g., 3272-26A>G) which allow synthesis of some normal CFTR mRNA (and protein), albeit at very low levels; and vi) class VI mutants (e.g., c.120del23 [9] or membrane-rescued F508del) impair the plasma membrane stability of CFTR.

Genomic Analysis and comparative genomics in reference to cystic fibrosis, sickle cell and Alzheimer’s diseases.

Increasing the activity of defective cystic fibrosis transmembranes conductance regulator (CFTR) protein is a potential treatment for cystic fibrosis. The life expectancy of people with cystic fibrosis (CF), a lethal inherited disease, has been greatly extended by advances in therapy. Currently, there are a number of potential drugs for treatment of CF lung disease in clinical trials. These therapies are targeted at all points in the pathogenesis of lung disease, from gene transfer to drugs that treat mucus, infection and inflammation in the airways. An exciting development is that of modulation of the abnormal protein that causes CF, the cystic fibrosis transmembrane conductance regulator (CFTR), where drugs are targeted at specific defects in CFTR transcription, processing or functioning. A number of antibacterial agents formulated for inhalation are at various stages of study or newly approved, which should improve options for chronic management of airway infection . Cystic fibrosis (CF) is a pleiotropic disease, originating from mutations in the CF transmembrane conductance regulator (CFTR). Both higher adherence to a Mediterranean-type diet and more physical activity have been independently associated with lower Alzheimer disease (AD) risk. Therefore comparative genomics analysis of these diseases is done. In this context Exons and CNS were observed in all three sequences. This paper provides information meant to increase an understanding of the public-health impact of cystic fibrosis, sickle cell and Alzheimer's diseases including incidence and prevalence, mortality, lifetime risks, costs, and impact on family caregivers.

CFTR mutation screening in an assisted reproductive clinic

Cystic fibrosis (CF) is the most common deleterious single-gene recessive disorder in non-Hispanic Caucasians. Mutations within the CF transmembrane receptor (CFTR) gene produce a variable phenotype, including pulmonary disease, pancreatic insufficiency, meconium ileus and infertility. Screening of antenatal/preconception patients to identify CFTR mutation carriers has been shown to reduce the incidence of CF-affected babies at birth. The application of preconception screening to assisted reproductive technology (ART) patients enables carrier couples a choice between prenatal screening and preimplantation genetic diagnosis (PGD). To screen patients entering an infertility clinic, for 30 common CFTR mutations, and to detect carrier patients prior to initiating assisted reproductive treatment. DNA from 5600 infertility patients was screened using a PCR/OLA kit for 30 CFTR mutations. All identified carriers and carrier couples were offered genetic counselling. Prenatal testing and PGD for CFTR mutations were offered to carrier couples where appropriate. A total of 5600 patients were screened for 30 CFTR mutations with 261 carriers being identified and at a significantly increased carrier rate of one in 21.5 (4.66% ± 0.55%). R117H/c.350G>A was significantly increased in this infertile population and accounted for 13.8% of all mutations identified. Twelve carrier couples were identified, and nine carrier couples had at least one cycle of PGD for CFTR mutations. The carrier rate of CFTR mutations is elevated in patients presenting for infertility treatment, and preconception screening should be encouraged in all patients entering ART clinics.

A Novel Exon Duplication of the Cystic Fibrosis Transmembrane Conductance Regulator in a Patient Presenting With Adult-Onset Recurrent Pancreatitis

Pancreatitis is a rare occurrence in patients with cystic fibrosis (CF) affecting 1.2% of all patients, but it can be the first presenting sign in approximately 15% of adults with pancreatic sufficiency and a milder CF phenotype. We report a case of a woman with recurrent pancreatitis who has one cystic fibrosis-causing mutation (G551D) and the first known description of a pathologic duplication of exon 19 of the CF transmembrane conductance regulator (CFTR). A 30-year-old white woman with 30 attacks of pancreatitis over a 5-year period starting at age 25 presented to the genetics department. She was found to have a mutation in the SPINK1 gene, IVS3+184T>A, and one cystic fibrosis-causing mutation (G551D) prompting full gene sequencing of the CFTR, revealing an additional duplication of exon 19. Sweat chloride testing was elevated at 97 and 106 mmol/L. Despite normal growth parameters and lung function, it is important to be aware of recurrent pancreatitis as a presenting sign of CF. Comprehensive CF gene analysis is necessary to detect a second CF-causing mutation that may put patients at risk for more severe symptoms of pancreatitis. There is a significant difference in the prevalence of heterozygote mutations between available testing methods.