Biomedical subjects
Publications and source records attributed to E Dequeker.
DNA-based testing for genetic diseases has developed from nothing into a principal part of laboratory medicine over the past 15 years. In the rush to bring these powerful new technologies into medical use, issues of quality have not always been given sufficient attention. Efforts are now being made to assess the quality of the output of genetic testing laboratories, and the results show that there is room for improvement.
To evaluate the quality of genetic testing for cystic fibrosis, 136, 145 and 159 laboratories participated in a European study in 1996, 1997 and 1998, respectively. We sent six purified DNA samples carrying the more common CFTR mutations with the request to test them using routine protocols. A panel of experts reviewed the results together with the raw data.
These recommendations for quality improvement of cystic fibrosis genetic diagnostic testing provide general guidelines for the molecular genetic testing of cystic fibrosis in patients/individuals. General strategies for testing as well as guidelines for laboratory procedures, internal and external quality assurance, and for reporting the results, including the requirements of minimal services in mutation testing, the nomenclature for describing mutations, procedures to control false-positive amplification reactions and to validate tests, and guidelines to implement a quality system in a molecular diagnostic laboratory are reviewed.
Within the framework of the European Concerted Action on Cystic Fibrosis (Biomed-2, BMH4-CT96-0462) a quality assessment was set up for 135 European and one Australian laboratory. Six DNA samples were sent to the various laboratories. These samples carried the following CFTR genotypes: dF508/N1303K; dI507/wild; dF508/G551D; dF508/621 + 1 GtoT; R553X/wild and 1717-1 GtoA/wild. Each laboratory was asked to process the samples as they routinely do, whether they checked for all mutations or not. More than 75% of the laboratories screened for at least six of these mutations. Heteroduplex analysis was the most frequently used primary testing method (47%), in many instances followed by restriction enzyme digestion. Only a minority of the laboratories made use of a commercial CFTR mutation detection kit. On average, 91% of the laboratories correctly typed both alleles of a given DNA sample. However, 35% of the laboratories incorrectly typed one or more alleles from a total of 12 alleles included in the trial. One laboratory even failed to identify four of the different alleles correctly. The genotyping error frequency tended to be lower in laboratories which perform more than 200 CFTR mutation analyses per year. The results of this quality control trial suggest that there are many laboratories (35%) which have a percentage of errors unacceptable in a routine testing setting. The development of a consensus testing strategy for routine diagnostic laboratories and centralised mutation analysis facilities for rare or country-specific mutations in a limited number of expert centres, in combination with regular training sessions and quality assessments, should further improve genotyping.