In vitro prediction of stop-codon suppression by intravenous gentamicin in patients with cystic fibrosis: a pilot study

BACKGROUND: Cystic fibrosis (CF) is caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein, which acts as a chloride channel activated by cyclic AMP (cAMP). The most frequent mutation found in 70% of CF patients is F508del, while premature stop mutations are found in about 10% of patients. In vitro aminoglycoside antibiotics (e.g. gentamicin) suppress nonsense mutations located in CFTR permitting translation to continue to the natural termination codon. Pharmacologic suppression of stop mutations within the CFTR may be of benefit to a significant number of patients. Our pilot study was conducted to determine whether intravenous gentamicin suppresses stop codons in CF patients and whether it has clinical benefits. METHODS: A dual gene reporter system was used to determine the gentamicin-induced readthrough level of the most frequent stop mutations within the CFTR in the French population. We investigated readthrough efficiency in response to 10 mg/kg once-daily intravenous gentamicin perfusions in patients with and without stop mutations. Respiratory function, sweat chloride concentration, nasal potential difference (NPD) and CFTR expression in nasal epithelial cells were measured at baseline and after 15 days of treatment. RESULTS: After in vitro gentamicin incubation, the readthrough efficiency for the Y122X mutation was at least five times higher than that for G542X, R1162X, and W1282X. In six of the nine patients with the Y122X mutation, CFTR immunodetection showed protein at the membrane of the nasal epithelial cells and the CFTR-dependent Cl(- )secretion in NPD measurements increased significantly. Respiratory status also improved in these patients, irrespective of the gentamicin sensitivity of the bacteria present in the sputum. Mean sweat chloride concentration decreased significantly and normalised in two patients. Clinical status, NPD and sweat Cl(- )values did not change in the Y122X patients with no protein expression, in patients with the other stop mutations investigated in vitro and those without stop mutations. CONCLUSION: Suppression of stop mutations in the CFTR gene with parenteral gentamicin can be predicted in vitro and is associated with clinical benefit and significant modification of the CFTR-mediated Cl(- )transport in nasal and sweat gland epithelium

Aspects évolutifs cliniques et radiologiques du syndrome R.A.V.I.NE.

STRASBOURG-Medecine (674822101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

La protéinose alvéolaire pulmonaire de l'enfant à La Réunion (à propos de quinze cas)

POITIERS-BU Médecine pharmacie (861942103) / SudocPARIS-BIUM (751062103) / SudocSAINT DENIS/REUNION-Droit Lettre (974112101) / SudocSudocFranceF

Cystic fibrosis at the Reunion Island (France): spectrum of mutations and genotype-phenotype for the Y122X mutation

Background: The Reunion Island is a French administrative department located in the Indian Ocean between the islands of Madagascar and Mauritius. Its population is known to be at a high risk of cystic fibrosis (CF). Methods: Data concerning all CF patients born at the Reunion Island was extracted from the French CF Registry. Twenty-eight DF508/DF508, 17 Y122X/DF508, and 11 Y122X/Y122X were included in a genotype – phenotype study. Results: The detection rate of the CFTR mutations was 83% among the CF patients born at the Reunion Island. Three CFTR mutations accounted for 75% of the detected CF alleles at the Reunion Island (DF508, Y122X, and 3120 + 1G→A.). The DF508/DF508, DF508/Y122X, and Y122X/Y122X genotypes accounted for 60.2% of the CF patients. Patients carrying at least one Y122X mutation were pancreatic insufficient, had high sweat chloride values and significantly lower anthropometric measures. The mean anthropometric values in all three groups were lower that in the whole CF population followed in ‘‘continental’’ France. This may reflect the poor compliance and even the refusal of treatment noted by the clinicians. Conclusions: The distribution of CFTR mutations could be explained by the history of the Reunion Island: admixture of French settlers, African and Asian populations, founder effect and isolation followed by genetic drift. The Y122X allele appears to be associated with a severe phenotype

Deletion of 5' sequences of the CSB gene provides insight into the pathophysiology of Cockayne syndrome.

Cockayne syndrome is an autosomal recessive neurodegenerative disorder characterized by a specific defect in the repair of UV-induced DNA lesions. Most cases of Cockayne syndrome are caused by mutations in the CSB gene but the pathophysiological mechanisms are poorly understood. We report the clinical and molecular data of two severely affected Cockayne patients with undetectable CSB protein and mRNA. Both patients showed severe growth failure, microcephaly, mental retardation, congenital cataracts, retinal pigmentary degeneration, photosensitivity and died at the ages of 6 and 8 years. UV irradiation assays demonstrated that both patients had the classical DNA repair defect. Genomic DNA sequencing of the CSB gene showed a homozygous deletion involving non-coding exon 1 and upstream regulatory sequences, but none of the coding exons. Functional complementation using a wild-type CSB expression plasmid fully corrected the DNA repair defect in transfected fibroblasts. Horibata et al recently proposed that all type of CSB mutations result in a defect in UV damage repair that is responsible for the photosensitivity observed in the syndrome, but that only truncated CSB polypeptides generated by nonsense mutations have some additional inhibitory functions in transcription or in oxidative damage repair, which are necessary to lead to the other features of the phenotype. Our patients do not fit the proposed paradigm and new hypotheses are required to account for the pathophysiology of Cockayne syndrome, at the crossroads between DNA repair and transcription

Chikungunya virus-associated encephalitis: a cohort study on La Réunion island, 2005-2009

International audienceObjectives: To estimate the cumulative incidence rate (CIR) of Chikungunya virus (CHIKV)-associated Central Nervous System (CNS) disease during the La Réunion outbreak, and assess the disease burden and patient outcome after three years.Methods: CHIKV-associated CNS disease was characterized retrospectively in a cohort of patients with positive CHIKV RT-PCR or anti-CHIKV IgM antibodies in the cerebrospinal fluid and fulfilling International Encephalitis Consortium criteria for encephalitis or encephalopathy. Neurological sequelae were assessed after three years.Results: Between September 2005 and June 2006, 57 patients were diagnosed with CHIKV-associated CNS disease, including 24 with CHIKV-associated encephalitis, the latter corresponding to a CIR of 8.6 per 100,000 persons. Patients with encephalitis were observed at both extremes of age categories. CIR per 100,000 persons were 187 and 37 in patients below 1 year and over 65 years, respectively, both far superior to those of cumulated causes of encephalitis in the USA in these age categories. The case fatality rate of CHIKV-associated encephalitis was 16.6% and the proportion of children discharged with persistent disabilities estimated between 30% and 45%. Beyond the neonatal period, the clinical presentation and outcomes were less severe in infants than in adults.Conclusions: In the context of a large outbreak, CHIKV is a significant cause of CNS disease. As with other etiologies, CHIKV-associated encephalitis case distribution by age follows a U-shaped parabolic curve

Pulmonary alveolar proteinosis in children on La Réunion Island: a new inherited disorder?

International audienc