Screening of CFTR mutations in an isolated population: identification of carriers and patients.

One important application of the identification of disease-causing mutations is carrier screening in the general population. Such a project requires a simple accurate test by which a large proportion of the mutations can be identified. This study describes screening for CFTR mutations in an isolated Israeli Arab village. Two mutations, G85E and delta F508, accounted for all the CF alleles of these patients. The screening program tested for these two mutations, as well as the 5T allele, which has recently been shown to down-regulate the CFTR expression and cause variable phenotype. The screened population comprised 497 students from one school, which all the children of the village attend. The results revealed high carrier frequency, 8.5%, for the two CFTR mutations, G85E and delta F508, and a carrier frequency of 12% for the 5T allele. Two compound heterozygotes for the CFTR mutations, delta F508/G85E and G85E/5T, were identified. Both of these students had not been diagnosed previously as having CF since their disease presentation was not typical of CF. The CF incidence in this village was found to be extremely high, 1:72 life births. The screening results were reported to the physicians of the village to be used, upon request, for genetic counselling. This study emphasizes the importance of such programs for the identification of non-classical patients and for carrier detection.

Efficacy of corticosteroids in acute bronchiolitis: short-term and long-term follow-up.

Corticosteroids continue to be used by many physicians to treat infants with bronchiolitis. The aim of this study was to examine the short-term and long-term efficacy of oral corticosteroid therapy when added to beta2-agonists in infants with mild to moderate bronchiolitis (defined as the first episode of wheezing associated with low grade fever, rhinitis, tachypnea, and increased respiratory effort in a previously healthy infant during the winter months). Infants with mild to moderate bronchiolitis, were randomly assigned to receive either oral prednisone (2 mg/kg/day) or placebo for 3 days. All patients received nebulized albuterol q.i.d. during this period. Upon admission and after 3 days of therapy, a clinical score was assigned based on respiratory rate, use of accessory muscle, and the presence of wheeze. Oxygen saturation (SaO2) was also measured. On day 7, we inquired as to the well-being of each child. Two years later, the development of chronic respiratory symptoms was assessed. Thirty-eight infants were enrolled in the study; 20 received prednisone and 18 received placebo. Both groups were similar in terms of age, duration of illness prior to enrollment, pretrial medication use, clinical severity of bronchiolitis, history of atopy, and family history of atopy. After 3 and 7 days of treatment, both groups showed similar clinical improvement and there were no statistically significant differences between the two groups in the clinical score or in the SaO2. No major side effects were observed. Two years later, 32% of the infants continued to suffer from chronic respiratory symptoms, with a similar prevalence in both groups. We conclude that a 3-day course of oral corticosteroids is of no benefit to infants with mild to moderate bronchiolitis who are also treated with an inhaled beta2-agonist.

A missense cystic fibrosis transmembrane conductance regulator mutation with variable phenotype.

OBJECTIVE: Cystic fibrosis (CF) has variable clinical presentation. Disease severity is partially associated with the type of mutation. The aim of this study was to report genotype-phenotype analysis of the G85E mutation. PATIENTS: The phenotype of 12 patients (8 were from the same extended family, and 5 of them were siblings from 2 families) carrying at least one copy of the G85E mutation was evaluated and compared with the phenotype of 40 patients carrying the two severe mutations, W1282X and/or DeltaF508 (group 1), and with 20 patients carrying the splicing mutation, 3849+10kb C->T, which was found to be associated with milder disease (group 2). RESULTS: A high phenotypic variability was found among the patients carrying the G85E mutation. This high variability was found among patients carrying the same genotype and among siblings. All the studied chromosomes carrying the G85E mutation had the 7T variant in the polythymidine tract at the branch/acceptor site in intron 8. Of the G85E patients, 25% had pancreatic sufficiency and none had meconium ileus, compared with 0% and 32%, respectively, of patients from group 1, and 80% and 0%, respectively, from group 2. Two patients carrying the G85E mutation had sweat chloride levels <60 mmol/L whereas all the others had typically elevated levels >80 mmol/L. Compared with group 2, patients carrying the G85E mutation were diagnosed at an earlier age and had higher sweat chloride levels, with mean values similar to group 1 but significantly more variable. Forced expiratory volume in 1 second (FEV1) was similar in the three groups, with no differences in the slope or in age-adjusted mean values of FEV1. The levels of transcripts lacking exon 9 transcribed from the G85E allele measured in 3 patients were 55%, 49%, and 35% and their FEV1 values were 82%, 83%, and 50% predicated, respectively. CONCLUSIONS: The G85E mutation shows variable clinical presentation in all clinical parameters. This variability could be seen among patients carrying on the other chromosome the same CFTR mutation, and also among siblings. This variability is not associated with the level of exon 9 skipping. Thus, the G85E mutation cannot be classified either as a severe or as a mild mutation.