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Annales de Biologie Clinique. Volume 62, Number 4, 465-70, Juillet-Août 2004, De mémoire d’interne

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Author(s) : B. Bonjean, L. Grollet, E. Visentin, F. Sigaux, J.‐M. Cayuela

Summary : Despite modern regimen of chemotherapy, one‐third of children with acute lymphoblastic leukaemia relapse. Recent studies have shown that a high level of minimal residual disease (MRD) at the end of induction is associated with an increased risk of relapse. We have developed and validated a real‐time PCR method (RQ‐PCR) to quantify MRD. We monitored 57 patients using IgH and TCR (Vδ2Dδ3) genes rearrangements as PCR targets. RQ‐PCR was performed with a primer and a TaqMan ® probe designed to consensus sequences in VH segments in combination with one allele specific oligonucleotide primer complementary to the junctionnal region. A sensitivity of 10 ‐‐4 was reached for 72% of the IgH alleles (n ∓ 50) and for 54,5% of the Vδ2Dδ3 alleles (n ∓ 22). We compared the results with those obtained by competitive PCR in 53 patients: no discordance between the two methods was observed. Seventeen patients were found positive (32%) and 27 negative (51%) with both techniques and 9 children (17%) were positive only with TaqMan technology. RQ‐PCR is more sensitive and more specific than competitive PCR. We thus propose that RQ‐PCR might be used in first intention for MRD analysis.

Keywords : childhood acute lymphoblastic leukaemia, minimal residual disease (MRD), real‐time quantitative PCR (RQ‐PCR), IgH and TCR rearrangements