RESUMEN
This is the third paper in the series providing updated information and recommendations for people with cystic fibrosis transmembrane conductance regulator (CFTR)-related disorder (CFTR-RD). This paper covers the individual disorders, including the established conditions - congenital absence of the vas deferens (CAVD), diffuse bronchiectasis and chronic or acute recurrent pancreatitis - and also other conditions which might be considered a CFTR-RD, including allergic bronchopulmonary aspergillosis, chronic rhinosinusitis, primary sclerosing cholangitis and aquagenic wrinkling. The CFTR functional and genetic evidence in support of the condition being a CFTR-RD are discussed and guidance for reaching the diagnosis, including alternative conditions to consider and management recommendations, is provided. Gaps in our knowledge, particularly of the emerging conditions, and future areas of research, including the role of CFTR modulators, are highlighted.
Asunto(s)
Regulador de Conductancia de Transmembrana de Fibrosis Quística , Fibrosis Quística , Humanos , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Fibrosis Quística/terapia , Fibrosis Quística/genética , Fibrosis Quística/diagnóstico , Nivel de Atención , Conducto Deferente/anomalías , Bronquiectasia/terapia , Bronquiectasia/diagnóstico , Bronquiectasia/etiología , Pancreatitis/terapia , Pancreatitis/diagnóstico , Pancreatitis/etiología , Aspergilosis Broncopulmonar Alérgica/diagnóstico , Aspergilosis Broncopulmonar Alérgica/terapia , Masculino , Enfermedades Urogenitales MasculinasRESUMEN
After three publications defining an updated guidance on the diagnostic criteria for people with cystic fibrosis transmembrane conductance regulator (CFTR)-related disorders (pwCFTR-RDs), establishing its relationship to CFTR-dysfunction and describing the individual disorders, this fourth and last paper in the series addresses some critical challenges facing health care providers and pwCFTR-RD. Topics included are: 1) benefits and obstacles to collect data from pwCFTR-RD are discussed, together with the opportunity to integrate them into established CF-registries; 2) the potential of infants designated CRMS/CFSPID to develop a CFTR-RD and how to communicate this information; 3) a description of the challenges in genetic counseling, with particular regard to phenotypic variability, unknown long-term evolution, CFTR testing and pregnancy termination 4) a proposal for the assessment of potential barriers to the implementation and dissemination of the produced documents to health care professionals involved in the care of pwCFTR-RD and a process to monitor the implementation of the CFTR-RD recommendations; 5) clinical trials investigating the efficacy of CFTR modulators in CFTR-RD and how endpoints and outcomes might be adapted to the heterogeneity of these disorders.
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Regulador de Conductancia de Transmembrana de Fibrosis Quística , Fibrosis Quística , Nivel de Atención , Humanos , Fibrosis Quística/terapia , Fibrosis Quística/genética , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Asesoramiento Genético , Pruebas Genéticas/métodos , Recién NacidoRESUMEN
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.
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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
The spectrum of disorders involving CFTR (cystic fibrosis transmembrane conductance regulator) dysfunction correlates with a continuous gradient of CFTR function defined by the combination of two allelic CFTR variants. CFTR-related disorders are clinical entities with features of cystic fibrosis (CF) and evidence for presence of CFTR dysfunction but not meeting criteria for diagnosis of CF. Individuals with CFTR-RDs demonstrate a wide range of CFTR activity and are still under-recognized or misclassified. The level of CFTR dysfunction may be measured in vivo (sweat testing, nasal potential difference measurements) and/or by ex vivo tests (intestinal current measurement), or indirectly indicated by CFTR variants, as alteration in sequence of the CFTR gene translates into CFTR dysfunction. CFTR bioassays can aid in the diagnosis of individuals with CF, but we lack parameters to differentiate CF from CFTR-RD. In the era of the CFTR modulators and their potential clinical benefit, it is of utmost importance to diagnose CFTR-RD as unambiguously as possible. We therefore propose the following to define compatible CFTR dysfunction in a person with a suspected diagnosis of CFTR-RD : (1) evidence of CFTR dysfunction in vivo or ex vivo in at least two different CFTR functional test types, or (2) One CFTR variant known to reduce CFTR function and evidence of CFTR dysfunction in vivo or ex vivo in at least two different CFTR functional test types, or (3) Two CFTR variants shown to reduce CFTR function, with at most one CF-causing variant.
Asunto(s)
Regulador de Conductancia de Transmembrana de Fibrosis Quística , Fibrosis Quística , Humanos , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Regulador de Conductancia de Transmembrana de Fibrosis Quística/metabolismo , Fibrosis Quística/diagnóstico , Fibrosis Quística/genética , Fibrosis Quística/terapia , Nivel de Atención , Sudor/metabolismo , Transporte Iónico , MutaciónRESUMEN
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.
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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
Since the cloning of the CFTR gene 30 years ago, research aiming at understanding how CFTR mutations translate to abnormal synthesis or function of the CFTR protein has opened the way to genomically-guided therapy to improve CFTR function. A CFTR potentiator to enhance CFTR channel function has been approved in 2012 for specific and quite rare mutations. Subsequently, combinations of a corrector to increase CFTR expression at the cell membrane, plus a potentiator, have been approved for patients homozygous for the p.Phe508del mutation. To obtain robust correction of CFTR, new combinations of drugs are being studied. A triple combination associating two correctors and one potentiator is very promising and if data of clinical trials are confirmed, it could be a robust and well tolerated CFTR modulator for patients bearing at least one p.Phe508del mutation. Many other strategies are also in development to make these genomically-guided treatments available to all patients with CF. © 2020 French Society of Pediatrics. Published by Elsevier Masson SAS. All rights reserved.
Asunto(s)
Fibrosis Quística/tratamiento farmacológico , Terapia Genética/métodos , Aminofenoles/uso terapéutico , Aminopiridinas/uso terapéutico , Benzodioxoles/uso terapéutico , Agonistas de los Canales de Cloruro/uso terapéutico , Fibrosis Quística/genética , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Combinación de Medicamentos , Humanos , Indoles/uso terapéutico , Mutación , Medicina de Precisión , Quinolonas/uso terapéutico , Fármacos del Sistema Respiratorio/uso terapéuticoRESUMEN
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.
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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
It is often challenging for the clinician interested in cystic fibrosis (CF) to interpret molecular genetic results, and to integrate them in the diagnostic process. The limitations of genotyping technology, the choice of mutations to be tested, and the clinical context in which the test is administered can all influence how genetic information is interpreted. This paper describes the conclusions of a consensus conference to address the use and interpretation of CF mutation analysis in clinical settings. Although the diagnosis of CF is usually straightforward, care needs to be exercised in the use and interpretation of genetic tests: genotype information is not the final arbiter of a clinical diagnosis of CF or CF transmembrane conductance regulator (CFTR) protein related disorders. The diagnosis of these conditions is primarily based on the clinical presentation, and is supported by evaluation of CFTR function (sweat testing, nasal potential difference) and genetic analysis. None of these features are sufficient on their own to make a diagnosis of CF or CFTR-related disorders. Broad genotype/phenotype associations are useful in epidemiological studies, but CFTR genotype does not accurately predict individual outcome. The use of CFTR genotype for prediction of prognosis in people with CF at the time of their diagnosis is not recommended. The importance of communication between clinicians and medical genetic laboratories is emphasized. The results of testing and their implications should be reported in a manner understandable to the clinicians caring for CF patients.
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Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Fibrosis Quística/genética , Análisis Mutacional de ADN , Humanos , Estado Nutricional/genética , Polimorfismo Genético , Pronóstico , Empalme de Proteína , Control de Calidad , Pruebas de Función Respiratoria , Terminología como AsuntoRESUMEN
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
The p.Val754Met variant, described in 1996 in a CF patient, has been considered a CF mutation. However, biochemical aspects, results of functional studies and, finally, the identification of a complex deletion removing exons 3 to 10 and 14b to 16 in cis of p.Val754Met in a CF patient, argue against a strong deleterious effect. An inventory through the French CF network of patients carrying p.Val754Met led to the registration of seven patients (CF: n=4; idiopathic chronic pancreatitis: n=3) and six healthy individuals, all heterozygous for the variation. Extensive CFTR gene analysis was carried out, including the search for large rearrangements and other possible mutations. The complex deletion, whose breakpoints are described here, was found only in the four CF patients, in association with the same haplotype. This data, added to the fact that the p.[Phe508del]+[Val754Met] genotype was found in a healthy individual, bring further arguments against the association of p.Val754Met with CF. We thus suggest looking for a possible complex allele whenever p.Val754Met is detected and considering it neutral regarding genetic counseling when found in isolation.
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Alelos , Aberraciones Cromosómicas , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Fibrosis Quística/genética , Adolescente , Adulto , Secuencia de Bases , Niño , Fibrosis Quística/diagnóstico , Análisis Mutacional de ADN , Femenino , Pruebas Genéticas , Haplotipos , Humanos , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Mutación Missense , Polimorfismo Genético , Eliminación de SecuenciaAsunto(s)
Investigación Biomédica , Fibrosis Quística , Conducta Cooperativa , Fibrosis Quística/diagnóstico , Fibrosis Quística/genética , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Francia , Política de Salud , Humanos , Recién Nacido , Mutación , Tamizaje Neonatal , Pruebas Prenatales no InvasivasRESUMEN
Isolated congenital bilateral absence of the vas deferens (CBAVD) is an autosomal recessive disorder which has recently been shown to be associated with cystic fibrosis (CF) mutations. As part of an effort to understanding the genetic basis of this disorder, we have analysed the entire coding sequence and all the intron/exon boundaries of the cystic fibrosis transmembrane conductance regulator (CFTR) gene from 45 azoospermic individuals with this phenotype. We were able to detect a CFTR gene defect in 86% of chromosomes from these subjects. In addition to identifying 9 novel CFTR gene mutations, we found that a surprisingly high proportion (84%) of men with CBAVD who are heterozygous for a CF mutation carry the intron 8 polypyrimidine 5T CFTR allele on one chromosome. We hypothesise that this tight and significant (p < 10(-6)) linkage reflects the very mild impact of this mutation on CFTR gene expression. Although genetic heterogeneity cannot be excluded, CBAVD patients in whom no CFTR mutation has been detected are likely to harbour additional unidentified mild mutations. These observations have implications for the genetic counselling of CBAVD patients and CF families, and couples undergoing in vitro fertilisation procedures.
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Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Intrones , Conducto Deferente/anomalías , Alelos , Análisis Mutacional de ADN , Electroforesis en Gel de Poliacrilamida/métodos , Heterocigoto , Humanos , Masculino , Mutación , Desnaturalización de Ácido NucleicoRESUMEN
The severity and type of clinical manifestations are variable in patients with cystic fibrosis (CF). The respiratory syndromes in these patients consist of lung infections associated with disseminated bronchiectasis (DB), asthma, and chronic obstructive pulmonary disease. To investigate the possible involvement of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in chronic pulmonary disease in adults, we studied 32 DB patients with a clinically isolated respiratory syndrome. Careful analysis of all the CFTR gene exons and their flanking regions revealed a significantly increased frequency of CFTR gene mutations in these patients. Thirteen CFTR gene mutations were identified in sixteen different alleles. Six of these mutations, which have previously been reported as CF defects, were found on nine alleles. A further four, two of which had not previously been described (D192N and 406-2 AdeltaC), are potentially disease-causing mutations. We also identified three rare substitutions (R31C, L997F, T1220I), which could be involved in mild CFTR gene disease. Four patients were compound heterozygotes, one carried two CFTR gene mutations (possibly allelic) and six were heterozygous for a mutation. These results indicate that CFTR gene mutations may play a role in bronchiectatic lung disease, possibly in a multifactorial context. These findings have implications for genetic counselling of DB patients and their families.
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Bronquiectasia/genética , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Mutación , Adulto , Anciano , Alelos , Bronquiectasia/etiología , Bronquiectasia/metabolismo , Estudios de Cohortes , Fibrosis Quística/complicaciones , Fibrosis Quística/genética , Fibrosis Quística/metabolismo , Regulador de Conductancia de Transmembrana de Fibrosis Quística/metabolismo , Análisis Mutacional de ADN , Femenino , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Fenotipo , Polimorfismo Genético , Sudor/químicaRESUMEN
A number of disorders related to cystic fibrosis have been described since the cloning of the cystic fibrosis gene, including infertility due to the congenital bilateral absence of the vas deferens. We have identified, in several patients, complex cystic fibrosis transmembrane conductance regulator genotypes like double-mutant alleles. We have now analyzed the structure-function relationships of one of these mutants, R74W-D1270N cystic fibrosis transmembrane conductance regulator, expressed in HeLa cells, to evaluate the contribution of each mutation in the phenotype. We found that R74W cystic fibrosis transmembrane conductance regulator appears to be a polymorphism, while D1270N cystic fibrosis transmembrane conductance regulator could be responsible for the congenital bilateral absence of the vas deferens phenotype. The combination of the two produced a more severe effect on the chloride conductance pathway as well as on the phenotype.
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Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Regulador de Conductancia de Transmembrana de Fibrosis Quística/metabolismo , Fibrosis Quística/genética , Polimorfismo Genético , Alelos , Sustitución de Aminoácidos , Animales , Línea Celular , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Regulador de Conductancia de Transmembrana de Fibrosis Quística/química , Genotipo , Células HeLa , Humanos , Mamíferos , Mutación Puntual , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Relación Estructura-Actividad , TransfecciónRESUMEN
Hyperechogenic fetal bowel is prenatally detected by ultrasound during the second trimester of pregnancy in 0.1-1.8% of fetuses. It has been described as a normal variant but has often been associated with severe diseases, notably cystic fibrosis (CF). The aim of our study was to determine the risk of CF in a prospective study of 641 fetuses with ultrasonographically abnormal fetal bowel and the residual risk when only one mutation is detected in the fetus. Fetal cells and/or parental blood cells were screened for CFTR mutations. Two screening steps were used, the first covering the mutations most frequently observed in French CF patients (mutation detection rate of 70-90%) and, when a CF mutation was detected, a DGGE-sequencing strategy. We observed a 3.1% risk of CF when a digestive tract anomaly was prenatally observed at routine ultrasound examination. The risk was higher when hyperechogenicity was associated with bowel dilatation (5/29; 17%) or with the absence of gall bladder (2/8; 25%). The residual risk of CF was 11% when only one CF mutation was detected by the first screening step, thereby justifying in-depth screening. Mutations associated with severe CF (DeltaF508 mutation) were more frequently observed in these ultrasonographically and prenatally detected CF cases. However, the frequency of heterozygous cases was that observed in the normal population, which demonstrates that heterozygous carriers of CF mutations are not at increased risk for hyperechogenic bowel. In conclusion, fetal bowel anomalies indicate a risk of severe cystic fibrosis and justify careful CFTR molecular analysis.
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Fibrosis Quística/genética , Intestinos/diagnóstico por imagen , Ultrasonografía Prenatal , Fibrosis Quística/diagnóstico , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , ADN/química , ADN/genética , Análisis Mutacional de ADN , Feto/anomalías , Frecuencia de los Genes , Genotipo , Humanos , Recién Nacido , Intestinos/embriología , Mutación , Fenotipo , Valor Predictivo de las Pruebas , Pronóstico , Factores de RiesgoRESUMEN
UNLABELLED: HYPOTHESES/OBJECTIVES:: In adults, purulent pansinusitis or nasal polyposis starting early in life or that is permanently infected or associated either with chronic bronchial infection, infertility, or situs inversus are uncommon. In these atypical cases of chronic sinusitis (ACS), a primary dysfunction of the mucociliary clearance can be suspected. Adult patients with ACS were therefore investigated to detect primary ciliary dyskinesia (PCD) or cystic fibrosis (CF). STUDY DESIGN: Open, prospective study. PATIENTS AND METHODS: Forty-two patients with ACS were investigated with ciliary beat frequency and ultrastructure analysis in nasal cells and cystic fibrosis transmembrane conductance regulator (CFTR) gene mutation analysis in blood leukocytes. RESULTS: The diagnosis of PCD was confirmed in seven (17%) patients. At least one CFTR gene mutation was detected in 16 (38%) patients. The diagnosis of CF was suggested in three (7%) compound heterozygous patients. Another 13 (31%) patients were heterozygous for a CFTR gene mutation or a complex allele. Comparison of clinical features of ACS showed that only a family history of chronic sinusitis (P <.01) or chronic bronchitis (P <.02) and the presence of diffuse bronchiectasis (P <.0001) or serous otitis media (P <.0001) were significantly more frequent in PCD patients than in patients carrying CFTR gene mutations or those without PCD or CFTR gene mutations. CONCLUSIONS: ACS should be considered a remarkable entity in which congenital abnormalities of epithelial cells are frequently detected (55% of patients). The higher frequency of mutations in ACS patients compared with the general population suggests that heterozygoty for CFTR gene mutation could be a sinusitis-causing status.
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Fibrosis Quística/complicaciones , Síndrome de Kartagener/complicaciones , Sinusitis/etiología , Adulto , Alelos , Bronquiectasia/complicaciones , Bronquiectasia/diagnóstico , Bronquitis Crónica/complicaciones , Bronquitis Crónica/diagnóstico , Enfermedad Crónica , Fibrosis Quística/diagnóstico por imagen , Fibrosis Quística/genética , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Análisis Mutacional de ADN , Heterocigoto , Humanos , Síndrome de Kartagener/diagnóstico , Mutación Puntual/genética , Estudios Prospectivos , Sinusitis/complicaciones , Sinusitis/diagnóstico por imagen , UltrasonografíaRESUMEN
Cystic fibrosis is the most frequent autosomic recessively inherited disease in the European population. The gene implicated in this disease was cloned in 1989 but the consequences of the biochemical defect in the cell have not been fully elucidated. To date, 500 mutations of this 230 kilobase gene have been identified. These molecular anomalies each have an effect on the encoded protein (CFTR) an ion channel which appears to play a role in regulator functions. Results of the gene cloning and research into the different mutations have led to the development of effective strategies for molecular diagnosis facilitating genetic counselling for families at risk and the identification of atypical forms of the disease.