Shorter telomeres correlate with an increase in the number of uniparental disomies in patients with chronic lymphocytic leukemia.

This study investigated the correlation of the extent of chromosomal aberrations including uniparental disomies (UPDs) by SNP-chip analysis and FISH to telomere length in 46 patients with CLL. CLL harboring high risk aberrations, i.e. deletions of 11q22-23 or 17p13, had significantly shorter telomeres (higher ΔTL) compared to patients with CLL without such abnormalities. Patients with high chromosomal aberration rates had a worse overall survival compared to cases with lower aberration rates. Interestingly, however, an increase was found in the number of UPDs with shorter telomeres. These findings support the idea that telomeres in CLL cells play a role in the overall chromosome stability and could be involved in the occurrence of UPDs.

The LMO2 -25 Region Harbours GATA2-Dependent Myeloid Enhancer and RUNX-Dependent T-Lymphoid Repressor Activity.

Lim domain only 2 (LMO2) is a transcriptional co-factor required for angiogenesis and the specification of haematopoietic cells during development. LMO2 is widely expressed within haematopoiesis with the exception of T-cells. Failure to downregulate LMO2 during T-cell maturation leads to leukaemia, thus underlining the critical nature of context-dependent regulation of LMO2 expression. We previously identified a distal regulatory element of LMO2 (element -25) that cooperates with the proximal promoter in directing haematopoietic expression. Here we dissected the functional activity of element -25 and showed it to consist of two modules that conferred independent and cell-type specific activities: a 3' myeloid enhancer and a 5' T-cell repressor. The myeloid enhancer was bound by GATA2 in progenitors and its activity depended on a highly conserved GATA motif, whereas the T-cell repressor moiety of element -25 was bound by the Core Binding Factor in T-cells and its repressive activity depended on a highly conserved RUNT motif. Since the myeloid enhancer and nearby downstream region is recurrently involved in oncogenic translocations, our data suggest that the -25 enhancer region provides an open chromatin environment prone to translocations, which in turn cause aberrant LMO2 expression in T-cells due to the removal of the adjacent T-cell repressor.

A certified plasmid reference material for the standardisation of BCR-ABL1 mRNA quantification by real-time quantitative PCR.

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 × 10(6), 1.08±0.11 × 10(5), 1.03±0.10 × 10(4), 1.02±0.09 × 10(3), 1.04±0.10 × 10(2) 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).