PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “CYSTIC FIBROSIS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29Linked to original sources
PubMed1999

Multiresistant non-fermentative gram-negative bacteria in cystic fibrosis patients: the results of an Italian multicenter study. Italian Group for Cystic Fibrosis microbiology.

We carried out an epidemiological study on 2717 patients seen on a regular basis at Italian Cystic Fibrosis Centers with the aim of defining the prevalence of multiresistant Gram-negative strains in Italy. We found 272 multiresistant strains out of 1560 Gram-negative strains isolated in 1012 Italian cystic fibrosis patients. From our results in Italian cystic fibrosis patients we may conclude: (1) the beta-lactam antibiotics are moderately active; ceftazidime is the most efficacious even if 59.9% of multiresistant strains are not sensitive to this drug; (2) the aminoglycosides are poorly efficacious; 93% of multiresistant strains are resistant in vitro to tobramycin; and (3) the quinolones, notwithstanding their relatively recent introduction into clinical practice, have very poor activity against multiresistant strains, 89.7% of which are not sensitive.

Adolescent↗
PubMed2005

Differential sensitivity of the cystic fibrosis (CF)-associated mutants G551D and G1349D to potentiators of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel.

The genetic disease cystic fibrosis (CF) is caused by loss of function of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel. Two CF mutants, G551D and G1349D, affect equivalent residues in the highly conserved LSGGQ motifs that are essential components of the ATP-binding sites of CFTR. Both mutants severely disrupt CFTR channel gating by decreasing mean burst duration (MBD) and prolonging greatly the interburst interval (IBI). To identify small molecules that rescue the gating defects of G551D- and G1349D-CFTR and understand better how these agents work, we used the patch clamp technique to study the effects on G551D- and G1349D-CFTR of phloxine B, pyrophosphate (PP(i)), and 2'-deoxy ATP (2'-dATP), three agents that strongly enhance CFTR channel gating. Phloxine B (5 microm) potentiated robustly G551D-CFTR Cl- channels by altering both MBD and IBI. In contrast, phloxine B (5 microm) decreased the IBI of G1349D-CFTR, but this effect was insufficient to rescue G1349D-CFTR channel gating. PP(i) (5 mm) potentiated weakly G551D-CFTR and was without effect on the G1349D-CFTR Cl- channel. However, by altering both MBD and IBI, albeit with different efficacies, 2'-dATP (1 mm) potentiated both G551D- and G1349D-CFTR Cl- channels. Using the ATP-driven nucleotide-binding domain dimerization model of CFTR channel gating, we suggest that phloxine B, PP(i) and 2'-dATP alter channel gating by distinct mechanisms. We conclude that G551D- and G1349D-CFTR have distinct pharmacological profiles and speculate that drug therapy for CF is likely to be mutation-specific.

Adenosine Triphosphate↗
PubMed1975

A new assay for cystic fibrosis factor: effects of sera from patients with cystic fibrosis in the in vitro electrical properaties of rat jejunum.

The in vitro electrical properties of rat jejunum were utilized to assay a factor or factors in serum from patients with cystic fibrosis (CF). Sera from patients with CF were found to decrease short circuit current (SCC) and the SCC response to glucose, and to increase electrical resistance. These effects were present in all 24 patients with CF and 10 of 14 parents of CF patients and absent from the serum of 21 control subjects. This quantitative technique provides an alternative to the ciliostatic assays for the detection of the CF factor or factors.

Animals↗
PubMed2005

Spliceosome-mediated RNA trans-splicing with recombinant adeno-associated virus partially restores cystic fibrosis transmembrane conductance regulator function to polarized human cystic fibrosis airway epithelial cells.

We previously reported that spliceosome-mediated RNA trans-splicing (SMaRT), using recombinant adenoviral vectors expressing pre-trans-splicing molecules (PTMs), could partially restore cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel activity to polarized human DeltaF508 CF airway epithelia. Although these studies proved that SMaRT could correct CFTR mRNA defects, recombinant adenoviral infection from the basolateral surface was required because of inefficient infection from the apical membrane. Hence, applications of SMaRT technology for CF gene therapy require further testing with alternative, more clinically viable, vector systems. Furthermore, because recombinant adeno-associated virus (rAAV) vectors have packing limitations with respect to the size of the CFTR transgene insert, SMaRT correction of CFTR has the added attraction of a smaller transgene cassette. In the present study, we investigated whether rAAV vectors could effectively rescue CFTR chloride conductance in polarized human CF airway epithelial cells, using a SMaRT approach. AAV vectors were generated to carry a PTM engineered to bind intron 9 of CFTR pre-mRNA and then trans-splice the normal sequence for human CFTR exons 10-24 into the endogenous pre-mRNA. Human CF polarized airway epithelia were infected from the apical membrane with rAAV2 or rAAV5 CFTR-PTM vectors in the presence of proteasome-modulating agents (doxorubicin and N-acetyl-L-leucinyl-L-leucinyl-L-norleucinal) to enhance transduction. Epithelia were then evaluated for cAMP-sensitive short-circuit currents 2 weeks postinfection. Levels of CFTR correction seen with rAAV2 (1.07 +/- 0.24 microA) and rAAV5 (0.90 +/- 0.20 microA) CFTR-PTM vectors were similar, representing conductance equivalent to 14.2 and 13.6% of that observed in non-CF human polarized epithelia, respectively. RT-PCR analysis demonstrated the existence of wild-type CFTR transcript in CFTR-PTM-corrected epithelia, whereas only DeltaF508 mRNA was detected in polarized cells infected with control rAAV LacZ-PTM vectors. These results provide evidence that rAAV vectors are capable of using SMaRT to correct CFTR function after apical infection of human CF airway epithelia. The ability of CFTR-PTM-mediated correction to maintain endogenous CFTR regulation of the transgene product may further improve the efficacy of gene therapy for CF.

Cystic Fibrosis Transmembrane Conductance Regulato↗
PubMed2004

Repeated adeno-associated virus serotype 2 aerosol-mediated cystic fibrosis transmembrane regulator gene transfer to the lungs of patients with cystic fibrosis: a multicenter, double-blind, placebo-controlled trial.

STUDY OBJECTIVES: The primary objective was to determine the safety and tolerability of repeated doses of aerosolized adeno-associated serotype 2 vector containing cystic fibrosis transmembrane conductance regulator (CFTR) complementary DNA (cDNA) [tgAAVCF], an adeno-associated virus (AAV) vector encoding the complete human CFTR cDNA. Secondary objectives included evaluation of pulmonary function assessed by spirometry, lung abnormalities by high-resolution CT (HRCT), airway cytokines, vector shedding, serum neutralizing antibody to AAV serotype 2 (AAV2), and gene transfer and expression in a subset of subjects undergoing bronchoscopy with bronchial brushings. DESIGN: Randomized, double-blind, placebo-controlled, phase II trial. SETTING: Eight cystic fibrosis (CF) centers in the United States. SUBJECTS: CF patients with mild lung disease, defined as FEV(1) > or =60% predicted. INTERVENTIONS: Subjects were randomized to inhale three aerosolized doses of 1 x 10(13) deoxyribonuclease-resistant particles of tgAAVCF or matching placebo at 30-day intervals using the Pari LC Plus nebulizer (PARI; Richmond, VA). MEASUREMENTS AND RESULTS: Of 42 subjects randomized, 20 subjects received at least one dose of tgAAVCF and 17 subjects received placebo. No difference in the pattern of adverse events or laboratory abnormalities was noted between the two treatment groups. Improvements in induced-sputum interleukin-8 (p = 0.03) and FEV(1) (p = 0.04) were observed at day 14 and day 30, respectively, in the group receiving tgAAVCF when compared to those receiving placebo. No significant differences in HRCT scans were noted. Vector shedding in sputum was observed at low levels up to 90 days after the third dose of vector. All subjects receiving tgAAVCF exhibited an increase (by at least fourfold) in serum AAV2-neutralizing antibodies and detectable levels in BAL fluid from five of six treated subjects undergoing BAL. Gene transfer but not gene expression was detected in a subset of six tgAAVCF subjects who underwent bronchoscopy. CONCLUSIONS: Repeat doses of aerosolized tgAAVCF were safe and well tolerated, and resulted in encouraging trends in improvement in pulmonary function in patients with CF and mild lung disease.

Administration, Inhalation↗
PubMed1998

Subepithelial fibrosis and degradation of the bronchial extracellular matrix in cystic fibrosis.

Cystic fibrosis is a genetic disease caused by mutations of the cystic fibrosis transmembrane conductance regulator gene. Chronic inflammation and proteolysis lead to progressive damage of the bronchial wall. Extracellular matrix determines the structural organization and the mechanical properties of lung airways. It was thus examined in nine patients with cystic fibrosis (six bronchial biopsies and three lobectomies) in order to assess its level of alteration. The submucosal changes in matrix protein distribution were analyzed by immunochemistry and electron microscopy: the subepithelial basal lamina was thinned; an acellular collagen fiber layer composed of interstitial collagens (types I and III) subtended by tenascin and devoid of elastin-associated microfibrils was deposited beneath the basal lamina; this dense fibrous deposit generally formed a thick layer and could extend into the bronchial wall; the bronchial elastic framework lost arborescent distribution and appeared slender, packed, or lacunar; ultrastructural observation gave evidence for elastic and collagenic fiber lysis. Proteolytic activity is probably the major cause of matrix degradation. Fibrosis appears as a repair process rather than as an active fibrogenesis. The reversibility of extracellular matrix alterations is an important challenge and various interventions such as anti-inflammatory treatments can be targeted to halt or reverse this degradation process.

Adolescent↗
PubMed1990

A cluster of cystic fibrosis mutations in the first nucleotide-binding fold of the cystic fibrosis conductance regulator protein.

The gene responsible for cystic fibrosis (CF) has recently been identified and is predicted to encode a protein of 1,480 amino acids called the CF transmembrane conductance regulator (CFTR). Several functional regions are thought to exist in the CFTR protein, including two areas for ATP-binding, termed nucleotide-binding folds (NBFs), a regulatory (R) region that has many possible sites for phosphorylation by protein kinases A and C, and two hydrophobic regions that probably interact with cell membranes. The most common CF gene mutation leads to omission of phenylalanine residue 508 in the putative first NBF, indicating that this region is functionally important. To determine whether other mutations occur in the NBFs of CFTR, we determined the nucleotide sequences of exons 9, 10, 11 and 12 (encoding the first NBF) and exons 20, 21 and 22 (encoding most of the second NBF) from 20 Caucasian and 18 American-black CF patients. One cluster of four mutations was discovered in a 30-base-pair region of exon 11. Three of these mutations cause amino-acid substitutions at residues that are highly conserved among the CFTR protein, the multiple-drug-resistance proteins and ATP-binding membrane-associated transport proteins. The fourth mutation creates a premature termination signal. These mutations reveal a functionally important region in the CFTR protein and provide further evidence that CFTR is a member of the family of ATP-dependent transport proteins.

Adenosine Triphosphate↗
PubMed1993

Identification of the M1101K mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and complete detection of cystic fibrosis mutations in the Hutterite population.

The Hutterite population is a genetic isolate with an increased incidence of cystic fibrosis (CF). Previously we identified three CF haplotypes defined by polymorphisms flanking the CF transmembrane conductance regulator (CFTR) gene. delta F508 was present on one of the haplotypes in only 35% of CF chromosomes. We hypothesized that the other two CF haplotypes, one of which was the most common and the other of which is rare, each harbored different non-delta F508 mutations. Single-strand conformation polymorphism analysis detected a missense mutation, M1101K, in both chromosomes of a Hutterite patient carrying the two non-delta F508 haplotypes. M1101K appears to have originated on an uncommon CFTR allele and to be infrequent outside the Hutterite population. The presence of M1101K on two haplotypes is likely the result of a CFTR intragenic recombination which occurred since the founding, 10-12 generations ago, of the Hutterite population. The crossover was located between exons 14a and 17b, an interval of approximately 15 kbp. delta F508 and M1101K accounted for all of the CF mutations in patients from 16 CF families representing the three subdivisions of the Hutterite population.

Adolescent↗
PubMed2006

Consequences of combining cystic fibrosis- and non-cystic fibrosis-derived Pseudomonas aeruginosa antibiotic susceptibility results in hospital antibiograms.

BACKGROUND: In preparing hospital antibiograms for individual organisms and antibiotics, laboratories often combine susceptibility data for isolates from a variety of sources and patient types. If results from patients with known resistance patterns that vary from normal are included, the overall susceptibility value for the institution could be misleadingly skewed. OBJECTIVE: To assess the degree of bias introduced into a hospital antibiogram by combining cystic fibrosis (CF) and non-CF isolates of Pseudomonas aeruginosa to produce one hospital-wide percent susceptible figure for each tested antibiotic. METHODS: A retrospective analysis was conducted of an academic, tertiary care medical center's microbiology database. We examined quarterly and annual susceptibility data from 2004, comparing non-CF data with combined susceptibility data for 10 antibiotics within each quarter, as well as those reported in the annual antibiogram. Differences were assessed for statistical significance using chi(2) testing with Bonferroni correction. RESULTS: Large differences were observed between non-CF and combined percent susceptible data in the 4 quarters (aminoglycosides 3% vs 20%, fluoroquinolones 2% vs 18%, respectively) and when comparing annual non-CF (n = 191) with annual combined (n = 266) data. With the annual figures, these differences were frequently statistically significant (70% vs 58%, 91% vs 83%, 85% vs 70%, and 72% vs 60% for gentamicin, tobramycin, amikacin, and gatifloxacin/levofloxacin, respectively; all p< or =0.01). CONCLUSIONS: Combining CF and non-CF P. aeruginosa susceptibility into one percent susceptibility value for all isolates may produce figures that underestimate the activity of some antibiotic classes against non-CF isolates. Clinicians may make less than optimal empiric antibiotic selection choices based on such data.

Anti-Bacterial Agents↗
PubMed1978

Calcium and sodium transport processes in patients with cystic fibrosis 2. Mg2+- dependent, Ca2+ ATPase activity in fibroblast membrane preparations from cystic fibrosis patients and controls.

Mg2+-dependent Ca2+-ATPase activity was determined in membrane preparations of fibroblasts grown from skin biopsies of cystic fibrosis patients and age-matched controls. This enzyme was stimulated by increasing free calcium concentrations with an apparent Kdiss for calcium of approximately 45 micron. Although there was a great deal of variation in Ca2+-ATPase activity observed between individual strains, there was a significant decrease in the maximal activation of the Ca2+-ATPase in membrane preparations of fibroblasts obtained from cystic fibrosis patients compared to the controls (P less than 0.05). This observation indicates that decreased Ca2+-ATPase activity is a generalized phenomenon in cystic fibrosis found in more than one cell-type. This decrease in Ca2+-ATPase activity may have a number of implications that may explain some of the manifestations of the disease.

Adenosine Triphosphatases↗
PubMed1991

Sequence analysis of the cystic fibrosis gene in patients with disseminated bronchiectatic lung disease. Application in the identification of a cystic fibrosis patient with atypical clinical course.

The diagnosis of classical cystic fibrosis (CF) is easily made by clinical assessment alone, but may be missed or delayed in cases with an atypical clinical course. In a recent major study the age at diagnosis varied between 2 months and 47 years. For diagnostic purposes we have investigated the cystic fibrosis transmembrane regulator (CFTR) gene in 10 adult patients (age 18 to 45 years) with chronic obstructive pulmonary disease since childhood or adolescence and bronchiectases disseminated through both lungs. Only one subject (a 29-year-old male) had exocrine pancreatic insufficiency (PI); all others were pancreatic-sufficient (PS). The first nucleotide (ATP)-binding fold of the CFTR was analyzed by direct sequencing of polymerase chain reaction (PCR)-amplified genomic DNA in these cases. Two patients with different phenotypes (one PI, one PS) were found to be homozygous for the common delta F508 mutation of the CFTR gene, which proved the diagnosis of cystic fibrosis in their cases and allowed genetic counselling. The PS patient had normal sweat tests and had not previously been recognized as having CF. Four other patients were heterozygous for delta F508, with no other mutation in exons 10 or 11 of the gene, and four patients had normal sequences of these exons. Because only about 70% of all CF chromosomes carry delta F508, the unexpectedly high frequency (4/8 = 50%) of heterozygosity for delta F508 among the non-delta F508/delta F508 patients with bronchiectases suggests that some of these might also have unrecognized CF with rare genotypes and mutations in any of the 22 exons not sequenced.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1996

Analysis of alternative splicing patterns in the cystic fibrosis transmembrane conductance regulator gene using mRNA derived from lymphoblastoid cells of cystic fibrosis patients.

Using in vitro amplification of cDNA by the polymerase chain reaction, we analyzed alternatively spliced events of cystic fibrosis transmembrane conductance regulator gene in lymphoblastoid cells. Ten alternatively spliced transcripts were identified using analysis of 6 overlapping segments of amplified cDNA, 4 of which have not been described previously. These include transcripts lacking exon 16, 17b, 22 and a transcript resulting from the use of a cryptic acceptor and donor splice sites. Moreover, in 2 cystic fibrosis (CF) patients bearing nonsense mutations E60X or W1282X, we observed that nonsense mutations are associated with an alteration of splice site selection in vivo resulting in exon skipping of constitutive exons or in the use of cryptic splice sites. In addition, even though lymphoblastoid cells are not the relevant tissue to address the question of the relationship between clinical respiratory phenotype and genotype, our results concerning adult CF patients (delta F508/ delta F508) suggest that individual-specific RNA splicing patterns could influence the severity of the CF pulmonary disease. If this phenomenon of alternative splicing events proves to be significant in CF and to be a common feature of disease genes, the study of RNA splicing could become an important tool for the analysis of the genotype-phenotype relationship in many inherited disorders.

Adult↗
PubMed1991

Expression of the cystic fibrosis transmembrane conductance regulator gene in the respiratory tract of normal individuals and individuals with cystic fibrosis.

The most common mutation of the cystic fibrosis transmembrane conductance regulator gene, CFTR, associated with the clinical disorder cystic fibrosis (CF) is called "delta Phe508," a triple-base deletion resulting in loss of phenylalanine at residue 508 of the predicted 1480-amino acid CFTR protein. In the context that the lung is the major site of morbidity and mortality in CF, we evaluated airway epithelial cells for CFTR mRNA transcripts in normal individuals, normal-delta Phe508 heterozygotes, and delta Phe508 homozygotes to determine if the normal and delta Phe508 CFTR alleles are expressed in the respiratory epithelium, to what extent they are expressed, and whether there are relative differences in the expression of the normal and abnormal alleles at the mRNA level. Respiratory tract epithelial cells recovered by fiberoptic bronchoscopy with a cytology brush demonstrated CFTR mRNA transcripts with sequences appropriately reflecting the normal and delta Phe508 CFTR alleles of the various study groups. CFTR gene expression quantified by limited polymerase chain reaction amplification showed that in normal individuals, CFTR mRNA transcripts are expressed in nasal, tracheal, and bronchial epithelial cells at approximately 1-2 copies per cell, more than 100-fold greater than in pharyngeal epithelium. Importantly, allele-specific hybridization studies demonstrated that the normal and delta Phe508 CFTR alleles are expressed in the respiratory epithelium in similar amounts.

Base Sequence↗
PubMed1999

Recombinant DNase in cystic fibrosis: a protocol for targeted introduction through n-of-1 trials. Scottish Cystic Fibrosis Group.

Nebulized recombinant human deoxyribonuclease (DNase) reduces sputum viscosity and improves lung function in some cystic fibrosis patients, but individual responses are unpredictable. The aim of this study was to investigate how DNase can be targeted to those cystic fibrosis patients who would benefit most. The Scottish Cystic Fibrosis Group agreed on a randomized, double-blind, placebo-controlled n-of-1 assessment protocol. Patients underwent a maximum of three 4-week assessment periods (2 weeks saline, 2 weeks DNase each). Measurements performed at hospital (exercise, oximetry and spirometry) and home (symptom scores) were used to derive a scoring system to discriminate maximally between DNase and placebo effects. The data on 89 4-week assessments in 52 patients were reported. Twenty-four patients have completed the assessment process (12 responders and 12 nonresponders) to date. Forced expiratory volume in one second (FEVI) was the best discriminator of response, rising by >200 mL after DNase in 33 of 89 (37%) assessments compared with 3 of 89 (3%) after saline. N-of-1 trials, while laborious, permitted genuine treatment effects to be quantified within individuals with confidence, permitting appropriate treatment targeting. This provides a model of how other new expensive therapies may be introduced to maximize patient benefit.

Adolescent↗
PubMed2000

Cystic fibrosis mutations lead to carboxyl-terminal fragments that highlight an early biogenesis step of the cystic fibrosis transmembrane conductance regulator.

Inefficient delivery of the cystic fibrosis transmembrane conductance regulator (CFTR) to the surface of cells contributes to disease in the majority of cystic fibrosis patients. Analysis of cystic fibrosis-associated missense mutations in the first nucleotide binding domain (NBD1), including A455E, S549R, Y563N, and P574H, revealed reduced levels of mature CFTR with elevated levels of carboxyl-terminal polypeptide fragments of 105 and 90 kDa. These fragments appear early in biogenesis and degrade rapidly in four distinct cell types tested including the bronchial epithelial IB3-1 cell line. They were detected at highest levels with CFTRA455E where the 105-kDa fragment accounted for 40% of newly synthesized polypeptide but for only 20 and 7% of nascent wild type and mutant DeltaF508 proteins, respectively. The bands represent core- and unglycosylated forms of the same CFTR fragment supporting that precursor forms are correctly inserted into the membrane of the endoplasmic reticulum. Proteolytic cleavage would be predicted to occur on the cytosolic face of the endoplasmic reticulum within the NBD1-R domain segment, but pharmacological testing did not support involvement of the 26 S proteasome. The examined missense mutations in NBD1 manifest differently than the major mutant, DeltaF508, and highlight a critical conformational aspect of biogenesis of CFTR.

Animals↗
PubMed1999

Expression of delta F508 cystic fibrosis transmembrane conductance regulator protein and related chloride transport properties in the gallbladder epithelium from cystic fibrosis patients.

Cystic fibrosis transmembrane conductance regulator (CFTR), the cystic fibrosis (CF) gene product, functions as an adenosine 3', 5'-cyclic monophosphate (cAMP)-regulated chloride channel in the apical membrane of biliary epithelial cells, including gallbladder epithelial cells. It has been shown that triangle upF508, the most common CF mutation, impedes CFTR trafficking to the apical surface of epithelial cells. To elucidate the mechanisms of CF biliary disease, we examined structural features, CFTR expression, and chloride transport properties in gallbladder epithelial cells from nine triangle upF508 homozygous liver transplant recipients. Three CF patients had microgallbladders, characterized by severe histological abnormalities. Microgallbladder epithelial cells displayed aberrant immunolocalization of CFTR and of other normally apical proteins in the lateral domain of their plasma membrane and in their cytoplasm. This pattern was mimicked by chronic cholecystitis in non-CF patients. In the 6 remaining CF patients, CFTR was predominantly apical in the gallbladder epithelium, consistent with the detection of a fully glycosylated form by Western blot. In CF as compared with non-CF gallbladder epithelial cells in primary culture, chloride efflux was lower in response to cAMP and tended to be higher in response to exogenous adenosine 5'-triphosphate (ATP). The CF cells exhibited a residual cAMP-dependent chloride secretion that was inversely correlated with ATP-induced chloride secretion, and almost completely blunted in the cells derived from microgallbladders. Our results suggest that epithelial structural alterations aggravate triangle upF508 CFTR mislocalization in the gallbladder epithelium. The associated decrease in residual cAMP-dependent chloride secretion may contribute to biliary damage despite the up-regulation of alternative chloride transport pathways.

Adolescent↗
PubMed2002

Five percent of normal cystic fibrosis transmembrane conductance regulator mRNA ameliorates the severity of pulmonary disease in cystic fibrosis.

Estimates of the level of transcripts from the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) gene required to develop a CF phenotype range from 4-20% of normal. Due to the importance of obtaining reliable data on this issue for therapeutic strategies, we developed a novel polymerase chain reaction-based method to quantify CFTR transcripts and applied it to the analysis of nasal epithelium RNA of five patients with CF and the 3272-26A>G/F508del genotype. We calculated that 8.2 +/- 0.84% of the total CFTR RNA present in these five patients is normal full-length CFTR mRNA. We then demonstrated (in nasal samples from F508del carriers, n = 30) that the abundance of full-length F508del CFTR transcripts is reduced compared with wild-type transcripts, and estimated that the average ratio of F508del/wild-type transcripts is 0.87 +/- 0.06. To determine the amount of full-length transcripts relative to levels found in normal individuals, we corrected for the lower abundance of the F508del transcripts and calculated that the five patients with CF have, on average, 4.7 +/- 0.45% of the normal level of wild-type CFTR mRNA. Because these patients have mild CF compared with F508del homozygotes, this CFTR mRNA level appears to be sufficient to avoid the severe complications of the disease.

Alternative Splicing↗