Mucosa-associated lymphoid tissue (MALT) lymphomas most frequently involve the gastrointestinal tract and are the most common subset of extranodal non-Hodgkin lymphoma (NHL). Here we describe overexpression of BCL10, a novel apoptotic signalling gene that encodes an amino-terminal caspase recruitment domain (CARD), in MALT lymphomas due to the recurrent t(1;14)(p22;q32). BCL10 cDNAs from t(1;14)-positive MALT tumours contained a variety of mutations, most resulting in truncations either in or carboxy terminal to the CARD. Wild-type BCL10 activated NF-kappaB but induced apoptosis of MCF7 and 293 cells. CARD-truncation mutants were unable to induce cell death or activate NF-kappaB, whereas mutants with C-terminal truncations retained NF-kappaB activation but did not induce apoptosis. Mutant BCL10 overexpression might have a twofold lymphomagenic effect: loss of BCL10 pro-apoptosis may confer a survival advantage to MALT B-cells, and constitutive NF-kappaB activation may provide both anti-apoptotic and proliferative signals mediated via its transcriptional targets.

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Summary. In myelodysplastic syndromes (MDS) different prognostic risk analysis systems based on clinical and morphological data are used for predicting survival. Data on diagnostic and prognostic relevance of karyotype aberrations have prompted the development of scores including cytogenetics. The aim of this study was to assess and compare the explanatory power of different scoring systems and to assess the additional explanatory power of cytogenetics by evaluating the clinical and laboratory data of MDS patients from a single institution. Data of 386 MDS patients was available, with cytogenetic analysis at time of diagnosis in 256. Clinical/morphological scores: Bournemouth, modi®ed Bournemouth and Du È sseldorf; and scores including cytogenetics: Lausanne±Bournemouth, Lille and the International Prognostic Scoring System (IPSS), were calculated and their predictive power was compared for both overall survival and preleukaemic duration. Each of the scores had signi®cant correlation on both endpoints. Calculating the prognostic value of different cytogenetic aberrations we found that differentiating between evidence for no aberration, single aberrations excluding chromosomes 7 and 8, aberrations on chromosomes 5, 7 or 8 and complex aberrations was important. These data were incorporated in a`prognostic index cytogenetics' (pi score). Cytogenetic scores signi®cantly improved the prognostic value of the best clinical/morphological score in regard to both overall survival and preleukaemic duration. In conclusion, our data further stress the importance of cytogenetics for predicting prognosis in MDS.

Summary. Abnormalities of the short arm of chromosome 12 (12p) are found in about 5% of acute nonlymphocytic leukaemias (ANLL) and myelodysplastic syndromes (MDS). They are described to be characteristic of secondary leukaemias, especially after prior mutagenic exposure, and to be associated with a poor prognosis. In our series of 59 patients with 12p abnormalities and ANLL or MDS, exposure to genotoxic agents was proven only in five patients, but in 13/44 patients ANLL evolved from an MDS. Patients with a small deletion del(12)(p11.2p13) having a mild clinical course were distinguished from those with a large del(12)(p11.2), additional chromosomal anomalies, and a poor clinical course. Among the 31 patients with translocations or dicentric chromosomes involving 12p, a group of eight with t/dic(12;13) was the most frequent and was associated with a poor prognosis. The clinical outcome was adverse in the majority of patients with complex karyotype abnormalities, but in some patients a milder clinical course seems likely. A new, hitherto undescribed, abnormality in an MDS case with a duplication dup(12)(p11.2p13) was the amplification of the signal of the yeast artificial chromosome (YAC) clone 964c10 (D12S736). In 38 cases with deletions or unbalanced translocations/dicentrics one YAC signal was lost. Five patients with balanced translocations demonstrated breakpoints within the YAC, containing the ETV6 (TEL) gene. The breakpoints were telomeric to the YAC 964c10 in seven cases and centromeric in one patient.

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