Open Access

Helen White, Liesbet Deprez, Philippe Corbisier, Victoria Hall, Feng Lin, Stéphane Mazoua, Stefanie Trapmann, Anni Aggerholm, Hajnalka Andrikovics, Susanna Akiki, Gisela Barbany, Nancy Boeckx, Anthony Bench, Mark Catherwood, Jean-Michel Cayuela, Sandra Chudleigh, Tim Clench, Dolors Colomer, Filomena Daraio, Stephanie Dulucq, Joanna Farrugia, Linda Fletcher, Letizia Foroni, Ros Ganderton, Gareth Gerrard, Eglė Gineikienė, Sandrine Hayette, Hakim El Housni, Barbara Izzo, Mattias Jansson, Petra Johnels, Tomas Jurcek, Veli Kairisto, Aytug Kizilors, Dong-Wook Kim, Thoralf Lange, Thomas Lion, Katerina Machova Polakova, Giovanni Martinelli, Sarah McCarron, Pauline A. Merle, Ben Milner, Gerlinde Mitterbauer-Hohendanner, Meital Nagar, Guillermina Nickless, Josep F. Nomdedéu, Dag A. Nymoen, Elisabeth Oppliger Leibundgut, Ugur Ozbek, Tadej Pajič, Heike Pfeifer, Claude Preudhomme, Kadri Raudsepp, Giuliana Romeo, Tomasz Sacha, Rodica Talmaci, Tasoula Touloumenidou, Vincent H. J. Van der Velden, Paula Waits, Lihui Wang, Elizabeth Wilkinson, Gill Wilson, Dörte Wren, Renata Zadro, Janine Ziermann, Katerina Zoi, Martin C. Müller, Andreas Hochhaus, Heinz Schimmel, Nicholas C. P. Cross, Hendrik Emons

• Serial quantification of BCR–ABL1 mRNA is an important therapeutic indicator in chronic myeloid leukaemia, but there is a substantial variation in results reported by different laboratories. To improve comparability, an internationally accepted plasmid certified reference material (CRM) was developed according to ISO Guide 34:2009. Fragments of BCR–ABL1 (e14a2 mRNA fusion), BCR and GUSB transcripts were amplified and cloned into pUC18 to yield plasmid pIRMM0099. Six different linearised plasmid solutions were produced with the following copy number concentrations, assigned by digital PCR, and expanded uncertainties: 1.08±0.13 × 106, 1.08±0.11 × 105, 1.03±0.10 × 104, 1.02±0.09 × 103, 1.04±0.10 × 102 and 10.0±1.5 copies/μl. The certification of the material for the number of specific DNA fragments per plasmid, copy number concentration of the plasmid solutions and the assessment of inter-unit heterogeneity and stability were performed according to ISO Guide 35:2006. Two suitability studies performed by 63 BCR–ABL1 testing laboratories demonstrated that this set of 6 plasmid CRMs can help to standardise a number of measured transcripts of e14a2 BCR–ABL1 and three control genes (ABL1, BCR and GUSB). The set of six plasmid CRMs is distributed worldwide by the Institute for Reference Materials and Measurements (Belgium) and its authorised distributors (https://ec.europa.eu/jrc/en/reference-materials/catalogue/; CRM code ERM-AD623a-f).