Distribution of CFTR mutations in the Czech population: positive impact of integrated clinical and laboratory expertise, detection of novel/de novo alleles and relevance for related/derived populations.

BACKGROUND: This two decade long study presents a comprehensive overview of the CFTR mutation distribution in a representative cohort of 600 Czech CF patients derived from all regions of the Czech Republic. METHODS: We examined the most common CF-causing mutations using the Elucigene CF-EU2v1™ assay, followed by MLPA, mutation scanning and/or sequencing of the entire CFTR coding region and splice site junctions. RESULTS: We identified 99.5% of all mutations (1194/1200 CFTR alleles) in the Czech CF population. Altogether 91 different CFTR mutations, of which 20 were novel, were detected. One case of de novo mutation and a novel polymorphism was revealed. CONCLUSION: The commercial assay achieved 90.7%, the MLPA added 1.0% and sequencing increased the detection rate by 7.8%. These comprehensive data provide a basis for the improvement of CF DNA diagnostics and/or newborn screening in our country. In addition, they are relevant to related Central European populations with lower mutation detection rates, as well as to the sizeable North American "Bohemian diaspora".

Variability in the use of CE-marked assays for in vitro diagnostics of CFTR gene mutations in European genetic testing laboratories.

DNA diagnostics of genetic diseases increasingly shifts towards utilization of commercial assays. Cystic fibrosis (CF)-related DNA diagnostics were used as a model for a pilot survey of the variability in the utilization of qualitative CE-marked in vitro diagnostic (IVD) assays and the scale of their modification by end users. A structured questionnaire, developed in the context of the EuroGentest project, was distributed within the frame of the 2005 annual CF external quality assessment (EQA) scheme. Its aim was to evaluate the variability in the use of different CE-marked IVD assays in routine CF DNA diagnostics. Survey results were analysed and sequentially discussed with respective users and/or manufacturers. In total, 125 responses from EQA scheme participants were received. Almost half of the respondents modified manufacturer-recommended protocols. They also reported sporadic and/or recurrent problems with assay performance and genotyping of particular alleles. Nonetheless, only half of the respondents performed in-house verification before the implementation of the assay in clinical diagnostics and/or after modification of the recommended protocol. Results of this survey substantiate the importance of guidelines for proper verification of CE-marked IVD assays in DNA diagnostics, using CF as a model.

Pilot newborn screening project for cystic fibrosis in the Czech Republic: defining role of the delay in its symptomatic diagnosis and influence of ultrasound-based prenatal diagnosis on the incidence of the disease.

The objective need for cystic fibrosis (CF) newborn screening (NBS) in the Czech Republic has recently been substantiated by a significant delay of its symptomatic diagnosis. This trend most likely resulted from the process of decentralisation of health care which led to the deterioration of care for patients who need specialised approaches. Applied newborn screening model (IRT/DNA/IRT) was efficacious enough to detect CF cases with median age at diagnosis of 37 days. The incidence of CF (1 in 6946 live births) ascertained in this project was lower than that established previously by epidemiological studies (1 in 2700-1 in 3300). However, adjustment for broadly applied ultrasound-based prenatal diagnosis (PND) in the 2nd trimester of pregnancy, that was performed within the period of the project (1/2/2005-2/11/2006), rendered an incidence estimate of 1 in 4023. This value is closer to that observed in other CF NBS programmes and reflects influence of PND on the incidence of CF.