Characterization of a pediatric T-cell acute lymphoblastic leukemia patient with simultaneous LYL1 and LMO2 rearrangements

Translocation of the LYL1 oncogene are rare in T-cell acute lymphoblastic leukemia, whereas the homologous TAL1 gene is rearranged in approximately 20% of patients. Previous gene-expression studies have identified an immature T-cell acute lymphoblastic leukemia subgroup with high LYL1 expression in the absence of chromosomal aberrations. Molecular characterization of a t(7;19)(q34;p13) in a pediatric T-cell acute lymphoblastic leukemia patient led to the identification of a translocation between the TRB@ and LYL1 loci. Similar to incidental T-cell acute lymphoblastic leukemia cases with synergistic, double translocations affecting TAL1/2 and LMO1/2 oncogenes, this LYL1-translocated patient also had an LMO2 rearrangement pointing to oncogenic cooperation between LYL1 and LMO2. In hierarchical cluster analyses based on gene-expression data, this sample consistently clustered along with cases having TAL1 or LMO2 rearrangements. Therefore, LYL1-rearranged cases are not necessarily associated with immature T-cell development, despite high LYL1 levels, but elicit a TALLMO expression signature.     

Blood flow in coronary artery bypass vein grafts: volume versus velocity at cardiovascular MR imaging

Forty-nine patients with previous bypass surgery underwent coronary angiography and cardiovascular magnetic resonance (MR) imaging of single-vein bypass grafts. Volume flow and velocity analyses were performed and compared on MR velocity maps. Bland-Altman analysis showed close agreement between the two types of analysis. Comparison of areas under the receiver operating characteristic curve revealed no significant differences between the analyses for detection of stenoses of 70% or greater. Diagnostic accuracy for volume flow and velocity parameters was 92% and 93%, respectively. Velocity analysis appears to be the preferred method, because it is less time-consuming and has a similar diagnostic accuracy to volume flow analysis.     

Neuromaturation of human locomotion revealed by non-dimensional scaling

When two fundamental gait parameters—step length and step frequency—are scaled non-dimensionally, thereby accounting for increases in a child's physical size, ontogenetic changes in the locomotor control strategy are revealed. We believe dimensionless velocity , the product of dimensionless step length and frequency, serves as a measure of neural development. It increases from the age of 18 months and reaches a plateau between 50 and 90 months, attaining the adult value of 0.45. Based on a study of 200 children, our findings lend support to a theory that posits a neuromaturation growth curve with the form: (t)=0.45 (1–e^–0.05t) where t is the age in months and 0.05 is the growth coefficient.     

Design and standardization of PCR primers and protocols for detection of clonal immunoglobulin and T-cell receptor gene recombinations in suspect lymphoproliferations: report of the BIOMED-2 Concerted Action BMH4-CT98-3936.

In a European BIOMED-2 collaborative study, multiplex PCR assays have successfully been developed and standardized for the detection of clonally rearranged immunoglobulin (Ig) and T-cell receptor (TCR) genes and the chromosome aberrations t(11;14) and t(14;18). This has resulted in 107 different primers in only 18 multiplex PCR tubes: three VH-JH, two DH-JH, two Ig kappa (IGK), one Ig lambda (IGL), three TCR beta (TCRB), two TCR gamma (TCRG), one TCR delta (TCRD), three BCL1-Ig heavy chain (IGH), and one BCL2-IGH. The PCR products of Ig/TCR genes can be analyzed for clonality assessment by heteroduplex analysis or GeneScanning. The detection rate of clonal rearrangements using the BIOMED-2 primer sets is unprecedentedly high. This is mainly based on the complementarity of the various BIOMED-2 tubes. In particular, combined application of IGH (VH-JH and DH-JH) and IGK tubes can detect virtually all clonal B-cell proliferations, even in B-cell malignancies with high levels of somatic mutations. The contribution of IGL gene rearrangements seems limited. Combined usage of the TCRB and TCRG tubes detects virtually all clonal T-cell populations, whereas the TCRD tube has added value in case of TCRgammadelta(+) T-cell proliferations. The BIOMED-2 multiplex tubes can now be used for diagnostic clonality studies as well as for the identification of PCR targets suitable for the detection of minimal residual disease.     

Polymerase chain reaction-based clonality testing in tissue samples with reactive lymphoproliferations: usefulness and pitfalls. A report of the BIOMED-2 Concerted Action BMH4-CT98-3936.

Lymphoproliferations are generally diagnosed via histomorphology and immunohistochemistry. Although mostly conclusive, occasionally the differential diagnosis between reactive lesions and malignant lymphomas is difficult. In such cases molecular clonality studies of immunoglobulin (Ig)/T-cell receptor (TCR) rearrangements can be useful. Here we address the issue of clonality assessment in 106 histologically defined reactive lesions, using the standardized BIOMED-2 Ig/TCR multiplex polymerase chain reaction (PCR) heteroduplex and GeneScan assays. Samples were reviewed nationally, except 10% random cases and cases with clonal results selected for additional international panel review. In total 75% (79/106) only showed polyclonal Ig/TCR targets (type I), whereas another 15% (16/106) represent probably polyclonal cases, with weak Ig/TCR (oligo)clonality in an otherwise polyclonal background (type II). Interestingly, in 10% (11/106) clear monoclonal Ig/TCR products were observed (types III/IV), which prompted further pathological review. Clonal cases included two missed lymphomas in national review and nine cases that could be explained as diagnostically difficult cases or probable lymphomas upon additional review. Our data show that the BIOMED-2 Ig/TCR multiplex PCR assays are very helpful in confirming the polyclonal character in the vast majority of reactive lesions. However, clonality detection in a minority should lead to detailed pathological review, including close interaction between pathologist and molecular biologist.     

Improved reliability of lymphoma diagnostics via PCR-based clonality testing: report of the BIOMED-2 Concerted Action BHM4-CT98-3936.

The diagnosis of malignant lymphoma is a recognized difficult area in histopathology. Therefore, detection of clonality in a suspected lymphoproliferation is a valuable diagnostic criterion. We have developed primer sets for the detection of rearrangements in the B- and T-cell receptor genes as reliable tools for clonality assessment in lymphoproliferations suspected for lymphoma. In this issue of Leukemia, the participants of the BIOMED-2 Concerted Action CT98-3936 report on the validation of the newly developed clonality assays in various disease entities. Clonality was detected in 99% of all B-cell malignancies and in 94% of all T-cell malignancies, whereas the great majority of reactive lesions showed polyclonality. The combined BIOMED-2 results are summarized in a guideline, which can now be implemented in routine lymphoma diagnostics. The use of this standardized approach in patients with a suspect lymphoproliferation will result in improved diagnosis of malignant lymphoma.     

TCRgammadelta+ large granular lymphocyte leukemias reflect the spectrum of normal antigen-selected TCRgammadelta+ T-cells.

T-cell large granular lymphocytes (LGL) proliferations range from reactive expansions of activated T cells to T-cell leukemias and show variable clinical presentation and disease course. The vast majority of T-LGL proliferations express TCRalphabeta. Much less is known about the characteristics and pathogenesis of TCRgammadelta+ cases. We evaluated 44 patients with clonal TCRgammadelta+ T-LGL proliferations with respect to clinical data, immunophenotype and TCR gene rearrangement pattern. TCRgammadelta+ T-LGL leukemia patients had similar clinical presentations as TCRalphabeta+ T-LGL leukemia patients. Their course was indolent and 61% of patients were symptomatic. The most common clinical manifestations were chronic cytopenias - neutropenia (48%), anemia (23%), thrombocytopenia (9%), pancytopenia (2%) - and to a lesser extent splenomegaly (18%). Also multiple associated autoimmune (34%) and hematological (14%) disorders were found. Leukemic LGLs were predominantly positive for CD2, CD5, CD7, CD8, and CD57, whereas variable expression was seen for CD16, CD56, CD11b, and CD11c. The Vgamma9/Vdelta2 immunophenotype was found in 48% of cases and 43% of cases was positive for Vdelta1, reflecting the TCR-spectrum of normal TCRgammadelta+ T-cells in adult PB. Identification of the well-defined post-thymic Vdelta2-Jdelta1 selection determinant in all evaluable Vgamma9+/Vdelta2+ patients, is suggestive of common (super)antigen involvement in the pathogenesis of these TCRgammadelta+ T-LGL leukemia patients.