Cystic Fibrosis :: diagnosis
Department of Pediatric Respiratory Medicine, Bristol Royal Hospital for Children, Upper Mauldin Street, Bristol, UK. email@example.com
Most cited papers:
Department of Genetics, Hospital for Sick Children, Toronto, Ontario, Canada.
Approximately 70 percent of the mutations in cystic fibrosis patients correspond to a specific deletion of three base pairs, which results in the loss of a phenylalanine residue at amino acid position 508 of the putative product of the cystic fibrosis gene. Extended haplotype data based on DNA markers closely linked to the putative disease gene locus suggest that the remainder of the cystic fibrosis mutant gene pool consists of multiple, different mutations. A small set of these latter mutant alleles (about 8 percent) may confer residual pancreatic exocrine function in a subgroup of patients who are pancreatic sufficient. The ability to detect mutations in the cystic fibrosis gene at the DNA level has important implications for genetic diagnosis.
A test for concentration of electrolytes in sweat in cystic fibrosis of the pancreas utilizing pilocarpine by iontophoresis.
Data from 17,857 patients with cystic fibrosis submitted in 1990 to the registry maintained by the Cystic Fibrosis Foundation were used to described their demographic characteristics, survival rates, pulmonary function, anthropometry, microbiologic data, complication rates, and health care utilization. Comparisons with similar data collected in 1969, 1972, and 1978 demonstrated a significant shift in the age distribution of patients with cystic fibrosis. The proportion of adult patients increased fourfold between 1969 (8%) and 1990 (33%). In 1990 the median age of all patients in the cystic fibrosis registry was 12.5 years; the median age at diagnosis was 7 months; cystic fibrosis was diagnosed in 90% of all patients by age 12 years. Meconium ileus at birth was reported for 16% of all patients with a new diagnosis in 1990. Median survival age doubled between 1969 and 1990, from 14 to 28 years. Female patients consistently had a lower median survival age than male patients (25 vs 30 years in 1990). The most frequently reported respiratory pathogen was Pseudomonas aeruginosa, cultured in specimens from 61% of all patients, ranging from 21% of those less than 1 year of age to more than 80% of those aged 26 years or older. Overall, patients with cystic fibrosis are living much longer than in the past but still have chronic pulmonary infections and other medical complications related to their disease, including diabetes, intestinal obstruction, cirrhosis, hemoptysis, and pneumothorax.
BACKGROUND: The pancreatic lesions of cystic fibrosis develop in utero and closely resemble those of chronic pancreatitis. Therefore, we hypothesized that mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene may be more common than expected among patients with chronic pancreatitis. METHODS: We studied 134 consecutive patients with chronic pancreatitis (alcohol-related disease in 71, hyperparathyroidism in 2, hypertriglyceridemia in 1, and idiopathic disease in 60). We examined DNA for 22 mutations of the CFTR gene that together account for 95 percent of all mutations in patients with cystic fibrosis in the northwest of England. We also determined the length of the noncoding sequence of thymidines in intron 8, since the shorter the sequence, the lower the proportion of normal CFTR messenger RNA. RESULTS: The 94 male and 40 female patients ranged in age from 16 to 86 years. None had a mutation on both copies of the CFTR gene. Eighteen patients (13.4 percent), including 12 without alcoholism, had a CFTR mutation on one chromosome, as compared with a frequency of 5.3 percent among 600 local unrelated partners of persons with a family history of cystic fibrosis (P<0.001). A total of 10.4 percent of the patients had the 5T allele in intron 8 (14 of 134), which is twice the expected frequency (P=0.008). Four patients were heterozygous for both a CFTR mutation and the 5T allele. Patients with a CFTR mutation were younger than those with no mutations (P=0.03). None had the combination of sinopulmonary disease, high sweat electrolyte concentrations, and low nasal potential-difference values that are diagnostic of cystic fibrosis. CONCLUSIONS: Mutations of the CFTR gene and the 5T genotype are associated with chronic pancreatitis.
Department of Pediatrics, University of Washington School of Medicine, Children's Hospital, Seattle, WA 98125, USA.
This comprehensive State of the Art review summarizes the current published knowledge base regarding the pathophysiology and microbiology of pulmonary disease in cystic fibrosis (CF). The molecular basis of CF lung disease including the impact of defective cystic fibrosis transmembrane regulator (CFTR) protein function on airway physiology, mucociliary clearance, and establishment of Pseudomonas aeruginosa infection is described. An extensive review of the microbiology of CF lung disease with particular reference to infection with P. aeruginosa is provided. Other pathogens commonly associated with CF lung disease including Staphylococcal aureus, Burkholderia cepacia, Stenotrophomonas maltophilia, Achromobacter xylosoxidans and atypical mycobacteria are also described. Clinical presentation and assessment of CF lung disease including diagnostic microbiology and other measures of pulmonary health are reviewed. Current recommendations for management of CF lung disease are provided. An extensive review of antipseudomonal therapies in the settings of treatment for early P. aeruginosa infection, maintenance for patients with chronic P. aeruginosa infection, and treatment of exacerbation in pulmonary symptoms, as well as antibiotic therapies for other CF respiratory pathogens, are included. In addition, the article discusses infection control policies, therapies to optimize airway clearance and reduce inflammation, and potential future therapies.
The diagnosis of cystic fibrosis: a consensus statement. Cystic Fibrosis Foundation Consensus Panel.
The diagnostic criteria proposed here are not likely to cover every possible clinical scenario, and there will be clinical dilemmas. For the vast majority of patients with CF, the diagnosis will be suggested by the presence of one or more characteristic clinical features, a history of CF in a sibling, or a positive newborn screening test result and will then be confirmed by laboratory evidence of CFTR dysfunction (Table V). Abnormal CFTR function will usually be documented by two elevated sweat chloride concentrations obtained on separate days or identification of two CF mutations. For patients in whom sweat chloride concentrations are normal or borderline and in whom two CF mutations are not identified, an abnormal nasal PD measurement recorded on 2 separate days can be used as evidence of CFTR dysfunction. Clinical judgment will continue to be essential in patients who have typical or "atypical" clinical features but who lack conclusive evidence of CFTR dysfunction. Such patients will require close clinical follow-up along with laboratory reevaluation as appropriate.
BACKGROUND: It is unknown whether genetic factors predispose patients to idiopathic pancreatitis. In patients with cystic fibrosis, mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene typically cause pulmonary and pancreatic insufficiency while rarely causing pancreatitis. We examined whether idiopathic pancreatitis is associated with CFTR mutations in persons who do not have lung disease of cystic fibrosis. METHODS: We studied 27 patients (mean age at diagnosis, 36 years), 22 of whom were female, who had been referred for an evaluation of idiopathic pancreatitis. DNA was tested for 17 CFTR mutations and for the 5T allele in intron 8 of the CFTR gene. The 5T allele reduces the level of functional CFTR and is associated with an inherited form of infertility in males. Patients with two abnormal CFTR alleles were further evaluated for unrecognized cystic fibrosis-related lung disease, and both base-line and CFTR-mediated ion transport were measured in the nasal mucosa. RESULTS: Ten patients with idiopathic chronic pancreatitis (37 percent) had at least one abnormal CFTR allele. Eight CFTR mutations were detected (prevalence ratio, 11:1; 95 percent confidence interval, 5 to 23; P<0.001). In three patients both alleles were affected (prevalence ratio, 80:1; 95 percent confidence interval, 17 to 379; P<0.001). These three patients did not have lung disease typical of cystic fibrosis on the basis of sweat testing, spirometry, or base-line nasal potential-difference measurements. Nonetheless, each had abnormal nasal cyclic AMP-mediated chloride transport. CONCLUSION: In a group of patients referred for evaluation of idiopathic pancreatitis, there was a strong association between mutations in the CFTR gene and pancreatitis. The abnormal CFTR genotypes in these patients with pancreatitis resemble those associated with male infertility.
B Richards, J Skoletsky, A P Shuber, R Balfour, R C Stern, H L Dorkin, R B Parad, D Witt, K W Klinger
Department of Genetic Disease Research, Integrated Genetics, Framingham, MA 01701.
Traditionally, DNA used for PCR-based diagnostic analysis has originated from white cells fractionated from whole blood. Although this method yields substantial quantities of DNA, there are some drawbacks to the procedure, including the inconvenience of drawing blood, risk of exposure to blood-borne pathogens, liquid sample handling, and the somewhat involved extraction procedure. Alternatively, DNA for genetic diagnosis has been derived from finger stick blood samples, hair roots, cheek scrapings, and urine samples. Oral saline rinses have also been used extensively as a means of collecting buccal epithelial cells as a DNA source. However, this method still requires liquid sample handling. Herein, we present our results involving the rapid extraction of DNA from buccal cells collected on cytology brushes and swabs for use in PCR reactions, specifically the multiplex amplification of 5 exons within the CFTR gene. The quality of DNA isolated from buccal cells, collected in this manner, has been sufficient to reproducibly support multiplex amplification. Cheek cell samples and the DNA prepared from them as described here are highly stable. The success rate of PCR amplification on DNA prepared from buccal cells is 99%. In a blind study comparing the analysis of 12 mutations responsible for cystic fibrosis in multiplex products amplified with DNA from both blood and buccal cell samples from 464 individuals, there was 100% correlation of results for blood and cheek cell DNA, validating the use of DNA extracted from cheek cells collected on cytology brushes for use in genetic testing.
D S Armstrong, K Grimwood, J B Carlin, R Carzino, J P Gutièrrez, J Hull, A Olinsky, E M Phelan, C F Robertson, P D Phelan
Department of Thoracic Medicine, Royal Children's Hospital, University of Melbourne, Parkville, Victoria, Australia. firstname.lastname@example.org
Airway inflammation is an important component of cystic fibrosis (CF) lung disease. To determine whether this begins early in the illness, before the onset of infection, we examined bronchoalveolar lavage (BAL) fluid from 46 newly diagnosed infants with CF under the age of 6 mo identified by a neonatal screening program. These infants were divided into three groups: 10 had not experienced respiratory symptoms or received antibiotics and pathogens were absent in their BAL fluid; 18 had clear evidence of lower respiratory viral or bacterial (> or = 10(5) CFU/ml) infection; and the remaining 18 had either respiratory symptoms, taken antibiotics, or had < 10(5) CFU/ml of respiratory pathogens. Their BAL cytology, interleukin-8, and elastolytic activity were compared with those from 13 control subjects. In a longitudinal study to assess if inflammation develops or persists in the absence of infection, the results of 56 paired annual BAL specimens from 44 CF infants were grouped according to whether they showed absence, development, clearance, or persistence of infection. In newly diagnosed infants with CF, those without infection had BAL profiles comparable with control subjects while those with a lower respiratory infection had evidence of airway inflammation. In older children, the development and persistence of infection was accompanied by increased inflammatory markers, whereas these were decreased in the absence, or with the clearance, of infection. We conclude that airway inflammation follows respiratory infection and, in young children, improves when pathogens are eradicated from the airways.
Birth of a normal girl after in vitro fertilization and preimplantation diagnostic testing for cystic fibrosis.
Institute of Obstetrics and Gynaecology, Royal Postgraduate Medical School, Hammersmith Hospital, London.
BACKGROUND. Cystic fibrosis is a common, severe autosomal recessive disease caused in a majority of cases by a three-nucleotide deletion (delta F508) in the cystic fibrosis transmembrane regulator gene. Current methods of prenatal diagnosis involve chorionic-villus sampling or amniocentesis. In vitro fertilization and diagnosis during embryonic development before implantation would allow only unaffected embryos to be selected for transfer to the uterus, thereby avoiding the need to terminate a pregnancy. METHODS. Preimplantation diagnosis of cystic fibrosis was attempted in the cases of three couples, both members of which carried the delta F508 deletion. In vitro fertilization techniques were used to recover oocytes from each woman and fertilize them with her husband's sperm. Three days after insemination, embryos in the cleavage stage underwent biopsy and removal of one or two cells for DNA amplification and analysis. RESULTS. Only two oocytes from one woman were fertilized normally; DNA analysis of one of the embryos failed and cystic fibrosis was diagnosed in the other (i.e., it was homozygous for delta F508), so neither was transferred. The oocytes of each of the other two women produced noncarrier, carrier, and affected embryos. Both couples chose to have one noncarrier embryo and one carrier embryo transferred. One woman became pregnant and gave birth to a girl free of the deletion in both chromosomes. CONCLUSIONS. Preimplantation diagnosis of the delta F508 deletion causing cystic fibrosis is possible through in vitro fertilization, biopsy of a cleavage-stage embryo, and amplification of DNA from single embryonic cells. This approach should be equally applicable to other single-gene diseases in which the defect has been identified. Analysis of a series of pregnancies, however, will be required to assess the method adequately.