The Italian External Quality Control Programme for cystic fibrosis molecular diagnosis: 4 years of activity.

Background: The Italian External Quality Control Programme for cystic fibrosis molecular diagnosis started in 2001; public laboratories distributed throughout Italy participated on a voluntary basis.

Methods: The Italian Public Health Institute (Istituto Superiore di Sanità) sent six validated DNA samples to participating laboratories: technical and clinical information was provided for each sample. Laboratories were required to analyse all six samples. For each sample the laboratories had to provide the results (including raw data) and a report of molecular analysis within 2 months using current methods and nomenclature. Raw data and reports were evaluated by a Steering Committee and their comments were sent to each laboratory.

Results: Genotyping results indicated a general good level of quality for all laboratories, i.e., approximately 1% of alleles were incorrectly assigned each year due to analytical (45%) and misinterpretation (45%) errors. During the first 2 years, more than 70% of laboratories did not test for some regional Italian mutations. Commercial kits for reverse dot-blot and oligonucleotide ligation assay PCR were used to detect mutations by 52.8% and 29.5%, respectively, of the participating laboratories. Reporting of results was still inadequate; in 2004 a model for the written report was introduced, but not all laboratories used it.

Conclusions: Our data show that few genotyping errors were made by laboratories and were principally due to misinterpretation and analytical reasons. However, reports are still inadequate and it will be interesting to evaluate the introduction of the reporting model in future years.