Case report: A novel TET2 mutation in a patient with refractory cytopenia with multilineage dysplasia.

Myelodysplastic syndrome diagnosis of karyotypically normal patients may be elusive because it relies exclusively on morphological and clinical data. In routine practice, finding of an acquired mutation or a cytogenetic abnormality provides irrefutable evidence of the clonal nature of that disease. Recurrent deletions and somatic mutations in TET2, a gene involved in epigenetic regulation, have been reported in about 20% of adult patients with myelodysplastic syndrome. We report a novel g.95805C>T, nonsense TET2 mutation, leading to a premature stop codon (p.Gln913*), in an adult patient with refractory cytopenia with multilineage dysplasia.

Genetic aberrations in multiple myeloma characterized by cIg-FISH: a Brazilian context.

Genetic abnormalities are critical prognostic factors for patients diagnosed with multiple myeloma (MM). This retrospective, multicenter study aimed to contribute with the genetic and clinical characterization of MM patients in a country with continental dimensions such as Brazil. Genetic abnormalities were assessed by cIg-fluorescent in situ hybridization (cIg-FISH) in a series of 152 MM patients (median age 55 years, 58.5% men). Overall, genetic abnormalities were detected in 52.7% (80/152) of patients. A 14q32 rearrangement was detected in 33.5% (n=51), including t(11;14), t(4;14) and t(14;16) in 18.4, 14.1, and 1% of cases, respectively. del(13q) was identified in 42.7% (n=65) of patients, of whom 49.2% (32/65) presented a concomitant 14q32 rearrangement. del(17p) had a frequency of 5.2% (n=8). del(13q) was associated with high plasma cell burden (≥50%, P=0.02), and del(17p) with advanced ISS stages (P=0.05) and extramedullary disease (P=0.03). t(4;14) was associated with advanced Durie-Salmon stages (P=0.008), renal insufficiency (P=0.01) and was more common in patients over 60 years old. This study reports similar frequencies of genetic abnormalities to most series worldwide, whereas the t(14;16) and del(17p), two high risk factors for newly diagnosed patients, exhibited lower frequencies. Our results expand the knowledge on the molecular features of MM in Brazil, a country where innovative therapies that could overcome a poor prognosis for some genetic abnormalities are not always available.

JAK2V617F mutation in patients with thrombosis: to screen or not to screen?

INTRODUCTION: Thrombotic complications are a main concern in patients with myeloproliferative neoplasms. Recently, a gain-of-function mutation of the gene encoding the JAK2 tyrosine kinase that results in a valine-to-phenylalanine substitution at position 617 (V617F) has been described. Since the description of the JAK2-V617F mutation and its finding in patients with splanchnic vein thrombosis without an overt myeloproliferative neoplasm, many groups have studied the prevalence of this mutation in patients with unexplained venous and arterial thrombosis. METHODS: A literature search was made using the key words thrombosis, JAK2V617F mutation, myeloproliferative neoplasms, cerebral vein thrombosis and splanchnic vein thrombosis. RESULTS: JAK2V617F is frequent in patients with splanchnic vein thrombosis, but is rare in patients with venous thrombosis at other locations or with arterial thrombosis. CONCLUSION: Routine testing for JAK2V617F is not currently recommended for patients with unexplained thromboses, except for those with splanchnic vein thrombosis. In patients with cerebral vein thrombosis, the value of testing for JAK2V617F mutation is yet to be established.

Genetic aberrations in multiple myeloma characterized by cIg-FISH: a Brazilian context

Genetic abnormalities are critical prognostic factors for patients diagnosed with multiple myeloma (MM). This retrospective, multicenter study aimed to contribute with the genetic and clinical characterization of MM patients in a country with continental dimensions such as Brazil. Genetic abnormalities were assessed by cIg-fluorescent in situ hybridization (cIg-FISH) in a series of 152 MM patients (median age 55 years, 58.5% men). Overall, genetic abnormalities were detected in 52.7% (80/152) of patients. A 14q32 rearrangement was detected in 33.5% (n=51), including t(11;14), t(4;14) and t(14;16) in 18.4, 14.1, and 1% of cases, respectively. del(13q) was identified in 42.7% (n=65) of patients, of whom 49.2% (32/65) presented a concomitant 14q32 rearrangement. del(17p) had a frequency of 5.2% (n=8). del(13q) was associated with high plasma cell burden (≥50%, P=0.02), and del(17p) with advanced ISS stages (P=0.05) and extramedullary disease (P=0.03). t(4;14) was associated with advanced Durie-Salmon stages (P=0.008), renal insufficiency (P=0.01) and was more common in patients over 60 years old. This study reports similar frequencies of genetic abnormalities to most series worldwide, whereas the t(14;16) and del(17p), two high risk factors for newly diagnosed patients, exhibited lower frequencies. Our results expand the knowledge on the molecular features of MM in Brazil, a country where innovative therapies that could overcome a poor prognosis for some genetic abnormalities are not always available.

p53 protein expression does not correlate with EBV status in childhood B non-Hodgkin lymphomas.

BACKGROUND: The p53 tumor suppressor gene is affected in a wide range of human cancers, including hematological malignancies. This gene encodes a nuclear phosphoprotein p53, which plays a key role in cell cycle arrest, induction of apoptosis, and DNA repair. Mutations of the p53 gene often lead to the accumulation of the mutated protein in the nucleus of neoplastic cells. However, p53 protein expression is frequently detected in non-Hodgkin lymphomas (NHL) without any correlation with p53 mutations. This discordance suggests the existence of other mechanisms to stabilize the p53 protein, including binding of p53 protein to viral proteins. p53 protein has been shown to bind to proteins encoded by the Epstein-Barr virus (EBV). PROCEDURE: The aim of this study was to analyze p53 expression in childhood B-NHL and correlate its expression in the absence of p53 mutations with EBV in order to investigate a possible involvement of EBV in p53 stabilization. DESIGNS AND METHODS: Tumor specimens from 35 children with B-NHL were analyzed by immunohistochemistry (IHC) with the DO7 monoclonal antibody, which recognizes an epitope at N-terminus of p53 protein and reacts with wild type and mutant proteins. To detect p53 mutations, PCR/SSCP and sequencing were performed. EBV status was determinated using a specific PCR technique. RESULTS: The overall frequency of p53 immunostaining positivity was 45% (16 of 35). p53 mutations were detected in nine patients (25.6%). p53 immunoreactivity was observed in all cases with mutations. Additionally, we identified 7 p53 positive cases among 26 tumors without mutations. EBV DNA was detected in 24 of 35 cases. Four patients with p53 expression dissociated from mutation were EBV positive. No statistically significant association was found between p53 expression and EBV cases despite the exclusion of those patients in which p53 expression was related with p53 mutations (P = 0.28 and 0.54, respectively). CONCLUSIONS: Our results suggested that in childhood B-NHL, the expression of p53 dissociated from mutations could not be related to EBV infection. Further studies with larger patient sets will be necessary to determinate if EBV-encoded protein may play a role for nuclear accumulation of p53 protein.

Molecular cloning of translocation t(1;14)(q21;q32) defines a novel gene (BCL9) at chromosome 1q21.

Abnormalities of chromosome 1q21 are common in B-cell malignancies and have been associated with a poor response to therapy. The nature of the involved gene(s) on chromosome 1q21 remains unknown. A cell line (CEMO-1) has recently been established from a patient with precursor-B-cell acute lymphoblastic leukemia (ALL), which exhibited a t(1;14)(q21;q32). To identify the gene involved in this translocation, we have cloned both rearranged IGHJ alleles using long-distance inverse polymerase chain reaction (LDI-PCR). Two IGHJ fragments were amplified from CEMO-1 DNA and sequenced. One allele showed novel sequences upstream of JH5 with no homology to either IGH or any other sequences on the databases. Using a single-copy Xho I fragment immediately 5' of JH5, PAC clones were isolated and mapped to chromosome 1q21 on normal metaphases by fluorescence in situ hybridization (FISH), confirming that this allele represented the t(1;14)(q21;q32) breakpoint. Sequence analysis of the 1q21 Xho I fragment showed identity with an expressed sequence tag (EST), and this probe was therefore used to probe Northern blots. Two transcripts of 6.3 kb and 4.2 kb expressed at low level in mRNA from all tissues were detected: a third transcript of 1.6 kb was expressed only in thymus, spleen, and small intestine. Full-length BCL9 cDNA clones were obtained from a normal human fetal brain cDNA library supplemented by 5' and 3' RACE. Sequence analysis predicted a protein of 1394 amino acids containing 18% proline, 11% glycine, 11% serine, and 6% methionine, but no recognizable protein motifs or significant homologies to any other known proteins. The CEMO-1 1q21 breakpoint fell within the 3' UTR of the BCL9 gene. Low-level expression of BCL9 was detected in Epstein-Barr virus-transformed normal B cells by Northern blot; in contrast, abundant BCL9 expression was observed in CEMO-1, indicating that deregulated expression of this gene was one pathological consequence of the translocation. Screening of a panel of 39 B-cell malignancies with 1q abnormalities by Southern blot showed one additional case with a breakpoint in the 3' UTR of BCL9, indicating that this was a recurrent breakpoint. FISH analysis using an 850-kb YAC spanning BCL9 identified a further case with t(1;22)(q21;q11) causing juxtaposition of BCL9 to the IGlambda locus. Other breakpoints were heterogeneous, falling both centromeric (10 cases) and telomeric (10 cases) of the BCL9 gene. These data suggest that BCL9 may be the target of translocation in some B-cell malignancies with abnormalities of 1q21 and that deregulated BCL9 expression may be important in their pathogenesis.