RESUMEN
We have conducted a large systematic study of 365 cystic fibrosis (CF) chromosomes in a Celtic population from Brittany, France, in which we have been able to identify more than 98% of the cystic fibrosis gene mutations. We detected 19 different CFTR mutations located in 9 exons. Eleven of these mutations have not been described previously and nine of them are presented in this study. The denaturing gradient gel electrophoresis strategy we have used, can be applied to other populations suggesting that population screening for CF on a large scale might be possible.
Asunto(s)
Fibrosis Quística/genética , Secuencia de Bases , Mapeo Cromosómico , Regulador de Conductancia de Transmembrana de Fibrosis Quística , ADN/genética , Análisis Mutacional de ADN , Etnicidad , Francia , Frecuencia de los Genes , Humanos , Proteínas de la Membrana/genética , Datos de Secuencia MolecularRESUMEN
BACKGROUND: The majority of variants of unknown clinical significance (VUCS) in the CFTR gene are missense variants. While change on the CFTR protein structure or function is often suspected, impact on splicing may be neglected. Such undetected splicing default of variants may complicate the interpretation of genetic analyses and the use of an appropriate pharmacotherapy. METHODS: We selected 15 variants suspected to impact CFTR splicing after in silico predictions on 319 missense variants (214 VUCS), reported in the CFTR-France database. Six specialized laboratories assessed the impact of nucleotide substitutions on splicing (minigenes), mRNA expression levels (quantitative PCR), synthesis and maturation (western blot), cellular localization (immunofluorescence) and channel function (patch clamp) of the CFTR protein. We also studied maturation and function of the truncated protein, consecutive to in-frame aberrant splicing, on additional plasmid constructs. RESULTS: Six of the 15 variants had a major impact on CFTR splicing by in-frame (n = 3) or out-of-frame (n = 3) exon skipping. We reclassified variants into: splicing variants; variants causing a splicing defect and the impairment of CFTR folding and/or function related to the amino acid substitution; deleterious missense variants that impair CFTR folding and/or function; and variants with no consequence on the different processes tested. CONCLUSION: The 15 variants have been reclassified by our comprehensive approach of in vitro experiments that should be used to properly interpret very rare exonic variants of the CFTR gene. Targeted therapies may thus be adapted to the molecular defects regarding the results of laboratory experiments.
Asunto(s)
Regulador de Conductancia de Transmembrana de Fibrosis Quística , Fibrosis Quística , Humanos , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Fibrosis Quística/tratamiento farmacológico , Fibrosis Quística/genética , Exones , Empalme del ARN/genética , Mutación Missense , MutaciónRESUMEN
Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease, but poorly studied in Africa. Its frequency in the University Clinic of Nephrology and Hemodialysis of Cotonou during the ten last years was 7 cases per year with a hospital prevalence estimated at 18 per 1000. The mean age of patients was 47.2 years extending from 29 to 70 years. Males were predominant with a sex ratio of 1.13. Family history was found in 47% of patients. The most common manifestations were lumbar pain (62%), high blood pressure (59%) urinary tract infections (53%), hematuria (46%), and abdominal masses (43%). Hepatic cysts were the most extra renal manifestations, found in 34% of cases. Renal failure was observed in 72% of patients of our series, six of them were under dialysis. Direct sequencing of polycystin 1 gene enabled us to identify some new mutations: 4 nonsense mutations (p.Q2824X exon 23, p.Q1651X exon 15, p.W1666X exon 15, p.R966W exon 12), a duplication (c_1761.1745 dup exon 9), a deletion (c.9397 + 1_9397 + 8del intron 26) and a deletion-insertion (c.7290_7291delins CTGCA exon 18).
Asunto(s)
Riñón Poliquístico Autosómico Dominante/genética , Canales Catiónicos TRPP/genética , Adulto , Distribución por Edad , Anciano , Benin/epidemiología , Codón sin Sentido/genética , Análisis Mutacional de ADN/métodos , Femenino , Predisposición Genética a la Enfermedad/genética , Humanos , Riñón/diagnóstico por imagen , Masculino , Persona de Mediana Edad , Mutagénesis Insercional/genética , Nefrología/estadística & datos numéricos , Riñón Poliquístico Autosómico Dominante/epidemiología , Reacción en Cadena de la Polimerasa/métodos , Prevalencia , Diálisis Renal , Eliminación de Secuencia/genética , Distribución por Sexo , Ultrasonografía , UniversidadesRESUMEN
BACKGROUND: Cystic fibrosis (CF) is caused by compound heterozygosity or homozygosity of CF transmembrane conductance regulator gene (CFTR) mutations. Phenotypic variability associated with certain mutations makes genetic counselling difficult, notably for R117H, whose disease phenotype varies from asymptomatic to classical CF. The high frequency of R117H observed in CF newborn screening has also introduced diagnostic dilemmas. The aim of this study was to evaluate the disease penetrance for R117H in order to improve clinical practice. METHODS: The phenotypes in all individuals identified in France as compound heterozygous for R117H and F508del, the most frequent CF mutation, were described. The allelic prevalences of R117H (p(R117H)), on either intron 8 T5 or T7 background, and F508del (p(F508del)) were determined in the French population, to permit an evaluation of the penetrance of CF for the [R117H]+[F508del] genotype. RESULTS: Clinical details were documented for 184 [R117H]+[F508del] individuals, including 72 newborns. The disease phenotype was predominantly mild; one child had classical CF, and three adults' severe pulmonary symptoms. In 5245 healthy adults, p(F508del) was 1.06%, p(R117H;T7) 0.27% and p(R117H;T5)<0.01%. The theoretical number of [R117H;T7]+[F508del] individuals in the French population was estimated at 3650, whereas only 112 were known with CF related symptoms (3.1%). The penetrance of classical CF for [R117H;T7]+[F508del] was estimated at 0.03% and that of severe CF in adulthood at 0.06%. CONCLUSIONS: These results suggest that R117H should be withdrawn from CF mutation panels used for screening programmes. The real impact of so-called disease mutations should be assessed before including them in newborn or preconceptional carrier screening programmes.
Asunto(s)
Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Fibrosis Quística/genética , Asesoramiento Genético , Heterocigoto , Tamizaje Neonatal , Penetrancia , Estudios Transversales , Fibrosis Quística/diagnóstico , Fibrosis Quística/epidemiología , Humanos , Recién Nacido , Estimación de Kaplan-Meier , Mutación , FenotipoRESUMEN
Newborn screening (NBS) for cystic fibrosis (CF) was implemented throughout France since 2002, with a 3-tiered strategy consisting in an immunoreactive trypsinogen (IRT) measurement at day-3, a search for the most common mutations responsible for CF when the IRT value is above the cut-off level, and, if necessary, a safetynet retesting of IRT at day-21. Coordination and follow-up are ensured at the national level and NBS is carried out through a regional organization involving NBS centers, biochemical and molecular genetics laboratories. Sweat testing and comprehensive mutation gene analysis are then performed according to a defined algorithm. Between 2002 and 2014, screening for the 30 most common mutations identified 87% of the alleles and comprehensive mutation gene analysis performed when applicable identified more than 300 additional mutations and resulted in a detection rate of 99.8% of the mutated alleles. Program surveillance ensured at a national level allowed to carry out adaptation of cut-off levels and removal of the p.Arg117His mutation. Thanks to these modifications, the performance of the French NBS program for CF meets the European guideline standards regarding positive predictive values, sensitivity and time to initial visit at the CF center, thus making the strategy effective. © 2020 French Society of Pediatrics. Published by Elsevier Masson SAS. All rights reserved.
Asunto(s)
Fibrosis Quística/diagnóstico , Tamizaje Neonatal , Algoritmos , Biomarcadores/metabolismo , Fibrosis Quística/genética , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Francia , Tamización de Portadores Genéticos , Asesoramiento Genético , Pruebas Genéticas , Política de Salud , Humanos , Recién Nacido , Mutación , Proteínas Asociadas a Pancreatitis/metabolismo , Sudor/químicaRESUMEN
BACKGROUND: Major issues of newborn screening (NBS) for CF are the assessment of disease liability of variants and of the penetrance of clinical CF, notably in inconclusive diagnosis. The penetrance of CF is defined as the risk of a particular genotype to lead to a CF phenotype. METHODS: We aimed to get insight into the penetrance of CF for fifteen CFTR variants: 5 frequent CF-causing and 10 classified as of varying clinical consequence (VCC) or associated with a CFTR-related disorder (CFTR-RD) in CFTR2 or CFTR-France databases. The penetrance was approached by: (1) comparison of variant allelic frequencies in CF patients (CFTR2) and in the general population; (2) estimation of the likelihood of a positive NBS test for the 14 compound heterozygous with F508del and the F508del homozygous genotypes, defined as the ratio of detected/expected number of neonates with a given genotype in the 2002-2017 period. RESULTS: A full penetrance was observed for severe CF-causing variants. Five variants were more frequently found in the general population than in CF patients: TG11T5, TG12T5, TG13T5, L997F and R117H;T7. The likelihood of a positive NBS test was 0.03% for TG11T5, 0.3% for TG12T5, 1.9% for TG13T5, 0.6% for L997F, 11.7% for D1152H, and 17.8% for R117H;T7. Penetrance varied greatly for variants with discrepant classification between CFTR2 and CFTR-France: 5.1% for R117C, 12.3% for T338I, 43.5% for D110H and 52.6% for L206W. CONCLUSION: These results illustrate the contribution of genetics population data to assess the disease liability of variants for diagnosis and genetic counselling purposes.
Asunto(s)
Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Fibrosis Quística/genética , Variación Genética , Tamizaje Neonatal , Penetrancia , Alelos , Femenino , Genotipo , Humanos , Recién Nacido , Masculino , FenotipoRESUMEN
BACKGROUND: The CFTR genotype remains incomplete in 1% of Cystic Fibrosis (CF) cases, because only one or no disease-causing variants is detected after extended analysis. This fraction is probably higher in CFTR-Related Disorders (CFTR-RD). Deep-intronic CFTR variants are putative candidates to fill this gap. However, the recurrence, phenotypic spectrum and full molecular characterization of newly reported variants are unknown. METHODS: Minigenes and analysis of CFTR transcripts in nasal epithelial cells were used to determine the impact on CFTR splicing of intronic variants that we previously identified by next generation sequencing of the whole CFTR locus. Phenotypic data were collected in 19 patients with CF and CFTR-RD, in whom one of the deep intronic variants has been detected. RESULTS: Three deep-intronic variants promoted the inclusion of pseudo-exons (PE) in the CFTR transcript, hindering the synthesis of a functional protein. The c.2989-313Aâ¯>â¯T variant, detected in four patients with CF or CFTR-RD from three different families, led to the inclusion of a 118â¯bp PE. The c.3469-1304Câ¯>â¯G variant promoted the inclusion of a 214â¯bp-PE and was identified in five patients with CF from four families. Haplotype analysis confirmed that this variant was associated with one CF chromosome of African origin. The most represented variant in our cohort was the c.3874-4522Aâ¯>â¯G, detected in 10 patients with various phenotypes, from male infertility to CF with pancreatic insufficiency. CONCLUSION: These three deep intronic CFTR variants are associated with a large phenotypic spectrum, including typical CF. They should be included in CF diagnostic testing and carrier screening strategies.
Asunto(s)
Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Regulador de Conductancia de Transmembrana de Fibrosis Quística/fisiología , Fibrosis Quística/complicaciones , Fibrosis Quística/genética , Adolescente , Adulto , Niño , Preescolar , Femenino , Variación Genética , Humanos , Lactante , Intrones , Masculino , Fenotipo , RecurrenciaRESUMEN
Newborn screening (NBS) of cystic fibrosis (CF) was implemented throughout the whole of France in 2002, but it had been established earlier in three western French regions. It can reveal atypical CF with one or two known CFTR mild mutations, with an uncertain evolution. The sweat test can be normal or borderline. In Brittany, from 1989 to 2004, 196 CF cases were diagnosed (1/2885 births). The incidence of atypical CF diagnosed by NBS is 9.7% (19 from 196). The outcome of 17 (2 lost of view) has been studied, with 9 other atypical CF cases diagnosed by NBS in two other regions. The follow-up period extends from 0.25 to 19.8 years (NBS implemented in Normandy in 1980) with mean age 4.6 years. The most frequent mild mutation is R117H ISV8-7T (50%). At the time of the last visit, nutritional status is normal. All these CF patients are pancreatic sufficient. Only one patient exhibits respiratory infections, whereas 7 others have them intermittently. Two of them had intermittent Pseudomonas aeruginosa colonization at 2.8 and 6.5 years. Mean Shwachman score is 96.7, mean Brasfield score is 22.8. Eight children have had lung function tests (mean follow-up of 10 years): mean FVC was 99% of predicted, mean FEV1 101%, but one of them has FEV1 of 48%. Predicting the phenotype of these atypical CF patients remains difficult, thus complicating any genetic counselling. A regular clinical evaluation is necessary, if possible by a CF unit, because CF symptoms may appear later.
Asunto(s)
Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Fibrosis Quística/sangre , Fibrosis Quística/diagnóstico , Fibrosis Quística/genética , Mutación , Tamizaje Neonatal/métodos , Adolescente , Niño , Preescolar , Fibrosis Quística/complicaciones , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Valor Predictivo de las Pruebas , Infecciones por Pseudomonas/complicaciones , Reproducibilidad de los ResultadosRESUMEN
Neonatal screening for cystic fibrosis (CF) can detect infants with elevated immunoreactive trypsinogen (IRT) levels and inconclusive sweat tests and/or CFTR DNA results. These cases of uncertain diagnosis are defined by (1) either the presence of at most one CF-associated cystic fibrosis transmembrane conductance regulator (CFTR) mutation with sweat chloride values between 30 and 59mmol/L or (2) two CFTR mutations with at least one of unknown pathogenic potential and a sweat chloride concentration below 60mmol/L. This encompasses various clinical situations whose progression cannot be predicted. In these cases, a sweat chloride test has to be repeated at 12 months, and if possible at 6 and 24 months of life along with extended CFTR sequencing to detect rare mutations. When the diagnosis is not definite, CFTR functional explorations may provide a better understanding of CFTR dysfunction. The initial evaluation of these infants must be conducted in dedicated CF reference centers and should include bacteriological sputum analysis, chest radiology, and fecal elastase assay. The primary care physicians in charge of these patients should be familiar with the current management of CF and should work in collaboration with CF centers. A follow-up should be performed in a CF reference center at 3, 6, and 12 months of life and every year thereafter. Any symptom indicative of CF requires immediate reevaluation of the diagnosis. These guidelines were established by the "neonatal screening and difficult diagnoses" working group of the French CF society. Their objective is to standardize the management of infants with unclear diagnosis.
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Fibrosis Quística/diagnóstico , Fibrosis Quística/terapia , Algoritmos , Estudios de Seguimiento , Humanos , Recién Nacido , Tamizaje NeonatalRESUMEN
Neonatal screening for cystic fibrosis (CF) may detect infants with elevated immunoreactive trypsinogen (IRT) levels but with inconclusive sweat tests and/or DNA results. This includes cases associating (1) either the presence of at most one CF-causing mutation and sweat chloride values between 30 and 59mmol/L or (2) two CFTR mutations with at least one of unknown pathogenicity and a sweat chloride below 60mmol/L. This encompasses different clinical situations whose progression cannot be predicted. These cases require redoing the sweat test at 12 months and if possible at 6 and 24 months of life. This must be associated with extended genotyping. CFTR functional explorations can also help by investigating CFTR dysfunction. These infants must be initially evaluated in dedicated CF centers including bacteriological sputum analysis, chest radiology and fecal elastase dosage. A home practitioner must be informed of the specificity of follow-up. These infants will be reviewed in the CF center at 3, 6 and 12 months and every year. Any CF-related symptom requires reevaluation of the diagnosis. These guidelines were established by the "neonatal screening and difficult diagnoses" working group of the French CF Society. They aim to standardize management of infants with unclear diagnosis in French CF centers.
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Fibrosis Quística/diagnóstico , Fibrosis Quística/terapia , Tamizaje Neonatal/métodos , Cloruros/sangre , Fibrosis Quística/genética , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Análisis Mutacional de ADN , Diagnóstico Diferencial , Estudios de Seguimiento , Humanos , Lactante , Recién Nacido , Comunicación Interdisciplinaria , Colaboración Intersectorial , Valor Predictivo de las Pruebas , Derivación y Consulta , Sudor/químicaRESUMEN
We report the prenatal diagnosis of a mosaic 45,X/46,X,r(X)/46,XX foetus after amniocentesis for maternal second-trimester serum screening. Biparental contribution for the X chromosomes suggest the postzygotic formation of the X ring. The ring is tiny but contains the X-inactive-specific transcript gene (XIST). However, we could not determine whether XIST was correctly expressed or not. The foetal ultrasound examination at 21, 25, 31 weeks' gestation showed no physical abnormalities, prompting the parents to continue the pregnancy. Physical examination at one year-old revealed normal growth and psychomotor development. Only three cases exhibiting an identical 45,X/46,X,r(X)/46,XX mosaicism, but detected postnatally, are reported in the literature. This is the first reported case ofa mosaic 45,X/46,X,r(X)/46,XX identified in the prenatal period.
Asunto(s)
Cromosomas Humanos X/genética , Enfermedades Fetales/diagnóstico por imagen , Mosaicismo , Diagnóstico Prenatal , Cromosomas en Anillo , Adulto , Femenino , Humanos , Fenotipo , Embarazo , Ultrasonografía , Inactivación del Cromosoma X/genéticaRESUMEN
Esophageal squamous cell carcinoma is a form of cancer occurring most commonly in males, particularly those living in some areas of Asia, Africa, and western Europe. In some of these tumors, a sequence alteration has been identified in the coding region of the TP53 gene which is known to inactivate the tumor suppressor function of its product. Using a GC clamp (i.e., a GC rich domain) denaturing gradient gel electrophoresis assay we have been able to identify sequence modifications in 27 of the 32 tumor samples analyzed (84%). Most of the mutations occur in exon 6, a region of the gene which has not previously been reported as being a hot spot for the mutations of other cancers. Twelve of the mutations reported here have not been described in other types of tumors and these consist mostly of frameshift or splice mutations. The distribution of mutations [transitions (45%), transversions (34%), and frameshift (21%)] suggests that the etiological contribution of genotoxic factors might be complex and might associate different exogenous and endogenous mutagen exposures.
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Carcinoma de Células Escamosas/genética , Neoplasias Esofágicas/genética , Genes p53 , Adulto , Anciano , Secuencia de Bases , Daño del ADN , Femenino , Humanos , Masculino , Persona de Mediana Edad , Datos de Secuencia Molecular , MutaciónRESUMEN
Cationic lipids are considered to be capable of efficiently and safely mediating DNA transfer into cells, although expression is transient. A new family of cationic lipids, called phosphonolipids, has been developed, with the relationship between the hydrophobic domain of the lipid molecules and the significant enhancement of transduction efficiency in a non-adherent cell line characterised in the present study. The kinetics of transfection efficiency were also investigated. Our results demonstrate that the peak of the transient expression of these reporter genes mediated by cationic lipids occurred within 3 to 14 days, depending on the aliphatic chain length of the complex used and on its formulation in the presence or absence of DOPE. Furthermore, the kinetics of transgene expression were found to differ in adherent and non-adherent cells. These results were obtained using three different techniques: CPRG, luminescence, and FACS-gal, and were in agreement with electron microscopy studies. We thus hypothesized that the plasma membrane composition of cells could affect the efficiency of transfection with cationic lipids. Our results suggest that phosphonolipids constitute a promising class of compounds for gene transfer protocols, and that galenic optimization should improve and modify the transfection efficiency of these DNA-lipid complexes.
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Sistema Hematopoyético/citología , Fosfolípidos , Transfección/métodos , Transgenes/genética , Cationes , Adhesión Celular , Separación Celular , Clorofenoles , Citometría de Flujo , Galactósidos , Expresión Génica , Humanos , Cinética , Leucemia Eritroblástica Aguda , Mediciones Luminiscentes , Microscopía Electrónica , Fosfolípidos/síntesis química , Plásmidos/ultraestructura , Proteínas Recombinantes de Fusión , Células Tumorales Cultivadas , beta-Galactosidasa/análisis , beta-Galactosidasa/genéticaRESUMEN
With the aim of developing new gene transfer tools for treating CF with gene therapy, we have synthesized a novel family of molecules named cationic phosphonolipids. The most efficient among them were selected by in vitro screening to compare their activities in vivo in mouse lungs. We used a reporter gene whose activity was measured cytofluorimetrically (FACS-Gal assay) and by means of a chemiluminescence technique. These tests allowed us to identify the percentage of transfected cells and to quantify total beta-galactosidase in the lungs. This enabled us to identify two molecules, significantly efficient in comparison with DNA alone: GLB73 (p = 0.0015) and GLB253 (p = 0.007). Their use resulted in a time lag between transfection and maximum efficiency: maximum efficiency was observed 4 days after transfection with GLB73, whereas it was noticeable only on day 7 with GLB253. Moreover, from toxicity studies carried out in vivo, GLB73 seems to be nontoxic. In vivo results were correlated with in vitro results obtained with CF epithelial cell lines. Consequently, GLB73 is a potential candidate for phase I clinical trials in humans.
Asunto(s)
Portadores de Fármacos , Técnicas de Transferencia de Gen , Pulmón/fisiología , Fosfolípidos/química , Animales , Citometría de Flujo/métodos , Mediciones Luminiscentes , Pulmón/patología , Ratones , Fosfolípidos/toxicidad , Relación Estructura-Actividad , beta-Galactosidasa/análisis , beta-Galactosidasa/genética , beta-Galactosidasa/metabolismoRESUMEN
The cystic fibrosis transmembrane conductance regulator (CFTR) gene, responsible for the cystic fibrosis phenotype when both alleles are mutated, was cloned and sequenced in 1989. Since then, more than 400 mutations have been reported in the gene, although most of these are rare. We have systematically analysed the entire coding sequence of the CFTR gene in a cohort of patients originating from the West of France (Caen, Brest and Nantes). More than 450 CF children, 914 chromosomes in all, have been exhaustively studied in the three centers. We have been able to characterize more than 90% of the mutations, respectively 93.5%, 99% and 95.8%. Despite the large diversity in the CFTR mutations occurring in CF patients from this area, these results can help to improve genetic counselling, prenatal diagnosis as well as our understanding of the molecular basis of the pathophysiology of cystic fibrosis.