http://repub.eur.nl/res/aut/9297/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/13892/ 2005-08-15T00:00:00Z Glucocorticoid sensitivity is an important prognostic factor in pediatric acute lymphoblastic leukemia (ALL). For its antileukemic effect, glucocorticoid binds the intracellular glucocorticoid receptor (GR) subsequently regulating transcription of downstream genes. We analyzed whether genetic variations within the GR gene are related to differences in the cellular response to glucocorticoids. METHODS: In leukemic samples of 57 children, the GR gene was screened for nucleotide variations using a PCR/single-strand conformational polymorphism sequencing strategy. Data were linked to in vivo and in vitro glucocorticoid resistance. RESULTS: No somatic mutations were detected in the GR gene coding region, but six polymorphisms (i.e., ER22/23EK, N363S, BclI, intron mutation 16 bp upstream of exon 5, H588H, and N766N) were identified. In 67% of ALL cases, at least one minor allele of these polymorphisms was detected. Although only borderline significant, the incidence for the N363S polymorphism minor allele was higher (12% versus 6%, P = 0.06) and for the ER22/23EK minor allele lower (4% versus 7.6%, P = 0.1) than in a healthy, comparable population. The different genotypes of the polymorphisms were not related to prednisone resistance. In conclusion, polymorphisms but not somatic mutations in the GR gene coding region occur in leukemic blasts of children with ALL. Our data suggest that these genetic variations are not a major contributor for differences in cellular response to glucocorticoids in childhood ALL. The higher incidence of the N363S minor allele and the lower incidence of the ER22/23EK minor allele in our ALL population as compared with a normal population warrants further research. http://repub.eur.nl/res/pub/8155/ 2002-01-01T00:00:00Z Immunoglobulin (Ig) and T-cell receptor (TCR) gene rearrangements are excellent patient-specific polymerase chain reaction (PCR) targets for detection of minimal residual disease (MRD) in acute lymphoblastic leukemia (ALL), but they might be unstable during the disease course. Therefore, we performed detailed molecular studies in 96 childhood precursor-B-ALL at diagnosis and at relapse (n = 91) or at presumably secondary acute myeloid leukemia (n = 5). Clonal Ig and TCR targets for MRD detection were identified in 94 patients, with 71% of these targets being preserved at relapse. The best stability was found for IGK-Kde rearrangements (90%), followed by TCRG (75%), IGH (64%), and incomplete TCRD rearrangements (63%). Combined Southern blot and PCR data for IGH, IGK-Kde, and TCRD genes showed significant differences in stability at relapse between monoclonal and oligoclonal rearrangements: 89% versus 40%, respectively. In 38% of patients all MRD-PCR targets were preserved at relapse, and in 40% most of the targets (> or = 50%) were preserved. In 22% of patients most targets (10 cases) or all targets (10 cases) were lost at relapse. The latter 10 cases included 4 patients with secondary acute myeloid leukemia with germline Ig/TCR genes. In 5 other patients additional analyses proved the clonal relationship between both disease stages. Finally, in 1 patient all Ig/TCR gene rearrangements were completely different between diagnosis and relapse, which is suggestive of secondary ALL. Based on the presented data, we propose stepwise strategies for selection of stable PCR targets for MRD monitoring, which should enable successful detection of relapse in most (95%) of childhood precursor-B-ALL