Characteristic Translocation Research Articles

Clear cell sarcoma: A case mimicking primary cutaneous malignant melanoma

Clear cell sarcoma (CCS) is a recently described variant of sarcoma characterized by prominent clear cells showing features similar to clear cell melanoma. This neoplasm was first described by Dr. Franz M. Erzinger. Primary CCS usually arises in deeper soft tissues, in association with fascia, tendons, or aponeuroses. Characteristic translocation t(12;22) (q13;q12) has been considered pathognomonic for CCS. Prognosis is related to tumor size. An early recognition and initial radical surgery is the key to a favourable outcome. We present a patient with an unusual neoplasm that resembled malignant melanoma.

Primitive neuroectodermal tumor of the kidney in an adult: a case report

IntroductionPrimitive neuroectodermal tumors (PNETs) occur predominantly in childhood preferentially in the soft tissues of the lower extremity and the paraspinal region. We present here a rare case of a PNET of the kidney in an adult.Case presentationA tumor adjacent to the right kidney was detected by ultrasound coincidentally at a routine check-up in a 46-year-old woman with irritable bowel syndrome in her medical history. The patient had no clinical signs. Contrast-enhanced computerized tomography scan of the abdomen demonstrated a highly vascularized renal tumor. A retroperitonealectomy with en-bloc resection of the kidney was performed, and histopathological work-up showed a primitive neuroectodermal tumor of the kidney with the characteristic translocation t(11;22)(q24;q12).ConclusionThis tumor entity must be accurately distinguished from other renal neoplasms because of the prognostic and therapeutic impact.

A20 deletion is associated with copy number gain at the TNFA/B/C locus and occurs preferentially in translocation‐negative MALT lymphoma of the ocular adnexa and salivary glands

The genetic basis of MALT lymphoma is largely unknown. Characteristic chromosomal translocations are frequently associated with gastric and pulmonary cases, but are rare at other sites. We compared the genetic profiles of 33 ocular adnexal and 25 pulmonary MALT lymphomas by 1 Mb array-comparative genomic hybridization (CGH) and revealed recurrent 6q23 losses and 6p21.2-6p22.1 gains exclusive to ocular cases. High-resolution chromosome 6 tile-path array-CGH identified NF-kappaB inhibitor A20 as the target of 6q23.3 deletion and TNFA/B/C locus as a putative target of 6p21.2-22.1 gain. Interphase fluorescence in situ hybridization showed that A20 deletion occurred in MALT lymphoma of the ocular adnexa (8/42=19%), salivary gland (2/24=8%), thyroid (1/9=11%) and liver (1/2), but not in the lung (26), stomach (45) and skin (13). Homozygous deletion was observed in three cases. A20 deletion and TNFA/B/C gain were significantly associated (p<0.001) and exclusively found in cases without characteristic translocation. In ocular cases, A20 deletion was associated with concurrent involvement of different adnexal tissues or extraocular sites at diagnosis (p=0.007), a higher proportion of relapse (67% versus 37%) and a shorter relapse-free survival (p=0.033). A20 deletion and gain at TNFA/B/C locus may thus play an important role in the development of translocation-negative MALT lymphoma.

The Interrelationship of Helicase and Nuclease Domains during DNA Translocation by the Molecular Motor EcoR124I

The type I restriction–modification enzyme EcoR124I comprises three subunits with the stoichiometry HsdR2/HsdM2/HsdS1. The HsdR subunits are archetypical examples of the fusion between nuclease and helicase domains into a single polypeptide, a linkage that is found in a great many other DNA processing enzymes. To explore the interrelationship between these physically linked domains, we examined the DNA translocation properties of EcoR124I complexes in which the HsdR subunits had been mutated in the RecB-like nuclease motif II or III. We found that nuclease mutations can have multiple effects on DNA translocation despite being distinct from the helicase domain. In addition to reductions in DNA cleavage activity, we also observed decreased translocation and ATPase rates, different enzyme populations with different characteristic translocation rates, a tendency to stall during initiation and altered HsdR turnover dynamics. The significance of these observations to our understanding of domain interactions in molecular machines is discussed.

Predictive gene profiles for breast cancer patients

To better understand the cellular origin of breast cancer, we developed a mouse model that recapitulates expression of the ETV6-NTRK3 (EN) fusion oncoprotein, the product of the t(12;15)(p13;q25) translocation characteristic of human secretory breast carcinoma. Activation of EN expression in mammary tissues by Wap-Cre leads to fully penetrant, multifocal malignant breast cancer with short latency. We provide genetic evidence that, in nulliparous Wap-Cre;EN females, committed alveolar bipotent or CD61+ luminal progenitors are targets of tumorigenesis. Furthermore, EN transforms these otherwise transient progenitors through activation of the AP1 complex. Given the increasing relevance of chromosomal translocations in epithelial cancers, such mice serve as a paradigm for the study of their genetic pathogenesis and cellular origins, and generation of preclinical models.

A novel five-way chromosomal translocation observed in chronic myelogenous leukemia

Most patients with chronic myelogenous leukemia (CML) show a Philadelphia (Ph) chromosome with a characteristic translocation between chromosomes 9 and 22. However, there are variant complex translocations involving other chromosomes in addition to the standard translocation. We describe a case of CML showing a complex and novel chromosomal translocation involving five chromosomes, t(4;12;7;9;22). ©2008 Elsevier Inc. All rights reserved.

Diagnosis and management of synovial sarcoma

Synovial sarcoma accounts about 9% of soft tissue sarcomas, most commonly develops in the extremity of young adults, is considered high grade and contains a characteristic translocation (X;18;p11;q11). While surgery and radiation therapy have achieved excellent local control, distant metastasis remains the principal problem limiting survival. Although ifosfamide based chemotherapy has been associated with an improved survival in patients with synovial sarcoma, the search for less toxic and more targeted systemic therapies is ongoing.

The Utility of Fluorescence In Situ Hybridization (FISH) in the Diagnosis of Myxoid Soft Tissue Neoplasms

Diagnosing myxoid soft tissue neoplasms can be challenging because of overlapping histologic features. Distinct chromosomal translocations have been identified in several myxoid sarcomas, including t(12;16)(q13;p11) FUS-DDIT3 in myxoid liposarcoma, t(7;16)(q34;p11) FUS-CREB3L2 in low-grade fibromyxoid sarcoma, and t(9;22)(q31;q12) EWSR1-NR4A3 in extraskeletal myxoid chondrosarcoma. These recurrent chromosomal alterations are attractive targets for diagnostic studies. To that end, dual-color, break-apart fluorescence in situ hybridization (FISH) probes spanning the genomic regions of EWSR1 (22q12), DDIT3 (12q13), and FUS (16p11) (Vysis, Downer's Grove, IL) were evaluated in formalin-fixed, paraffin-embedded tissues from myxoid neoplasms, including intramuscular myxoma (n=10), myxoid liposarcoma (n=18), low-grade fibromyxoid sarcoma (n=10), extraskeletal myxoid chondrosarcoma (n=13), and myxofibrosarcoma (n=8). Of the myxoid liposarcomas, 18/18 cases had a rearrangement of the DDIT3 gene, with 17/18 (94.4%) showing both DDIT3 and FUS gene rearrangements. A FUS gene rearrangement was identified in 7/10 (70%) of low-grade fibromyxoid sarcomas, with no changes involving EWSR1 or DDIT3. An EWSR1 translocation was seen in 6/13 (46.2%) of extraskeletal myxoid chondrosarcomas, without changes in DDIT3 or FUS genes. The remaining neoplasms studied showed no rearrangements involving DDIT3, FUS, or EWSR1 genes. In conclusion, interphase FISH using DDIT3 and FUS probes identifies the characteristic translocation in myxoid liposarcoma. FUS and EWSR1 probes are useful in confirming the diagnosis of low-grade fibromyxoid sarcoma and extraskeletal myxoid chondrosarcoma, respectively. The specificity of the probes is documented as none of the non-translocation-associated myxoid tumors showed genomic abnormalities with the probes tested. FISH is capable of providing specific ancillary information useful in this often difficult differential diagnosis.

ETV6-NTRK3 Fusion Oncogene Initiates Breast Cancer from Committed Mammary Progenitors via Activation of AP1 Complex

To better understand the cellular origin of breast cancer, we developed a mouse model that recapitulates expression of the ETV6-NTRK3 (EN) fusion oncoprotein, the product of the t(12;15)(p13;q25) translocation characteristic of human secretory breast carcinoma. Activation of EN expression in mammary tissues by Wap-Cre leads to fully penetrant, multifocal malignant breast cancer with short latency. We provide genetic evidence that, in nulliparous Wap-Cre;EN females, committed alveolar bipotent or CD61(+) luminal progenitors are targets of tumorigenesis. Furthermore, EN transforms these otherwise transient progenitors through activation of the AP1 complex. Given the increasing relevance of chromosomal translocations in epithelial cancers, such mice serve as a paradigm for the study of their genetic pathogenesis and cellular origins, and generation of preclinical models.

A Novel Variant of SYT-SSX1 Fusion Gene in a Case of Spindle Cell Synovial Sarcoma

Synovial sarcoma (SS) is a rare soft-tissue tumor that affects children and young adults. It is characterized by chromosomal translocation t(X;18)(p11.2;q11.2), which results in the fusion of the gene SYT on chromosome 18 with SSX genes on chromosome X. Heterogeneity within SS fusion junctions is rare. We report a case of a 9-year-old boy with a high-grade spindle cell sarcoma. Reverse transcriptase-polymerase chain reaction revealed a characteristic translocation of SSs. However, this sarcoma showed a longer-than-expected PCR product after gel electrophoresis. Direct sequencing of the product disclosed a novel SYT/SSX1 fusion transcript. Detection of fusion transcripts is useful for diagnostics of SS. In each case, when considering this diagnosis on the morphologic grounds an attempt to analyze the translocation using PCR should be made, including the recognition of its uncommon variants.

Primary Ewing Sarcoma of the Brain

Ewing sarcoma, along with peripheral primitive neuroectodermal tumor, belongs to a tumor family that shares clinicopathologic and molecular genetic features, including the characteristic chromosomal translocation that results in the fusion of the EWS gene on 22q12 to either the FLI1 gene on 11q24 or other Ets family transcription factor gene, such as the ERG gene on 21q22. In contrast, such translocations are not found in central primitive neuroectodermal tumors (cPNETs), such as medulloblastoma and supratentorial PNET. Ewing sarcoma has only rarely been noted to primarily involve the central nervous system-extraosseous Ewing sarcoma (CNS-EES). We report a case of a 7-year-old girl with an anterior cranial fossa mass. Pathology showed a primitive small blue cell tumor with focal Homer Wright rosette formation. The positive membranous immunostaining for CD99 and the EWS-FLI1 fusion demonstrated by fluorescence in situ hybridization studies confirmed the diagnosis of CNS-EES. Although CNS-EES may look identical to cPNETs, these tumors differ in histogenesis, molecular characteristics, and clinical behavior. Demonstration of characteristic translocations by molecular studies differentiates CNS-EES from cPNET and help clinicians make informed decisions regarding therapy.

Cytogenetic and molecular studies of an unusual case of multiple primary alveolar rhabdomyosarcomas: Low-level chromosomal instability and reciprocal translocation t(6;11)

Cytogenetic and molecular studies have shown that approximately 80% of cases of alveolar rhabdomyosarcoma (ARMS) have consistent chromosomal translocation of either t(2;13) or t(1;13), resulting in either PAX3–FKHR or PAX7–FKHR gene fusions. However, 20% of the cases diagnosed histologically are negative for these fusion genes. The clinical and pathological properties of the so-called fusion gene negative tumors remain to be defined. We present an unusual case of a 7-year-old boy who developed three separate primary ARMS over a 5-year period, with the first tumor diagnosed at the age of 12 months. The tumors were negative for the characteristic translocations, t(2;13) or t(1;13), but showed evidence of low-level chromosomal instability and a reciprocal chromosomal translocation t(6;11)(q27;q13). PCR amplification of the p53 gene, exons 2–11, followed by DNA sequencing did not detect any germline p53 mutation. These clinical and cytogenetic features have not been reported previously in ARMS. The findings suggest that cytogenetic abnormalities of chromosome 6 may be associated with the development of early onset multiple ARMS in a subgroup of pediatric patients as seen in this case.

Molecular cytogenetic characterization of four previously established and two newly established Ewing sarcoma cell lines

Most Ewing family tumors are identified by the characteristic translocation t(11;22)(q24;q12), resulting in a fusion protein EWS/FLI1 that acts as an aberrant transcription factor. In a minority of cases, the EWS gene is fused to another member of the ETS gene ( ERG, ETV1, E1AF, and FEV). Though the oncogenic transforming capability of the EWS/FLI1 protein is highly suggestive, the exact pathway behind remains to be elucidated. The availability of cell lines may help in the understanding of underlying cellular processes. In this study, we have established two new Ewing sarcoma cell lines and characterized them with molecular cytogenetic tools. This technology was also applied on four other previously published Ewing sarcoma cell lines. Our findings in relation to previous data on similar tumors are discussed.

The role of genetic testing in soft tissue sarcoma

Soft tissue tumours represent a heterogeneous group of mesenchymal lesions and their classification continues to evolve as a result of incorporating advances in cytogenetic and molecular techniques. In the last decade traditional diagnostic approaches were supplemented with a significant number of reliable molecular diagnostic tools, detecting tumour type-specific genetic alterations. In addition, the successful application of some of these techniques to formalin-fixed paraffin-embedded tissue made it possible to subject a broader range of clinical material to molecular analysis. Thus, molecular genetics has already become an integral part of the work-up in some tumours, such as paediatric small blue round cell tumours, which demonstrate characteristic translocations. Several lines of evidence suggest that sarcomas can be divided into two major genetic groups: (i) sarcomas with specific genetic alterations and usually simple karyotypes, such as reciprocal chromosomal translocations (e.g. FUS-DDIT3 in myxoid liposarcoma) and specific oncogenic mutations (e.g. KIT mutation in gastrointestinal stromal tumours); and (i) sarcomas with non-specific genetic alterations and complex unbalanced karyotypes. Some of these genetic abnormalities, including chromosomal numerical changes, translocations, gene amplifications or large deletions can be apparent at the cytogenetic level (karyotyping, fluorescence in situ hybridization), while others, such as small deletions, insertions or point mutations, require molecular genetic techniques (polymerase chain reaction and sequence analysis). This review focuses on the applicability of genetic testing in the diagnosis and prognosis of soft tissue sarcomas, and gives a realistic appraisal of the ancillary role of molecular techniques, including its advantages and limitations.

Towards the Human Cancer Genome Project: A Sequence-Ready Physical Map of a Follicular Lymphoma Genome.

With the aim of identifying and sequencing mutations in follicular lymphoma genomes, we have begun a project to generate at least 24 deeply redundant sequence-ready Bacterial Artificial Clone (BAC) - based whole genome maps, each from a different individual's lymphoma. BAC-array CGH and Affymetrix whole-genome sampling assays (WGSA) will be used along with the mapping data to identify genomic amplifications and losses in the lymphomas. Results from the mapping and array studies will be used to prioritize BAC clones for sequence analysis. Because each map will span essentially the entire genome of the corresponding lymphoma, we anticipate that essentially all regions of each tumor genome will be represented in easily sequenced BAC clones. This approach facilitates targeted sequencing of genomic regions of interest, including those containing genes relevant to cancer or harboring amplifications or deletions.Our mapping strategy hinges on the successful creation of deeply redundant high quality BAC libraries from primary lymphomas and large scale high throughput restriction enzyme fingerprinting of individual BACs with a version of the technology we used to map the human, mouse, rat and other genomes. The effort is large-scale, and will result in the generation of at least 2.5 million fingerprinted BAC clones over the next three years. Using the fingerprints, we will align the BACs to the reference human genome to assess genome coverage and to identify candidate genome rearrangements. In parallel, we will assemble the fingerprints into genome maps, looking for larger-scale genome variations between the lymphoma maps and the reference genome sequence. To test the feasibility of our approach, we obtained two restriction digest fingerprints from each of 140,000 individual BAC clones. BACs were sampled from a 7-fold redundant BAC library that had been created from genomic DNA purified from a primary follicular lymphoma sample. The fingerprints are being assembled into a clone map with the intent of reconstructing the entire tumor genome. 90,377 fingerprinted clones with unambiguous single alignments to the reference sequence were automatically assembled into 15,538 contigs. Subsequent rounds of semi-automatic contig merging further reduced the number of contigs to 5,433. Only 1,241 clones remained unassembled. We anchored the tumor genome map to the reference human genome sequence by aligning the clone fingerprints to the restriction map computed from the reference sequence assembly. As a result of this, we identified a BAC that captured the canonical t(14;18) translocation characteristic of follicular lymphomas. We sequenced this BAC and confirmed that it contains the expected translocation.Almost 2.6 gigabases (~91%) of the reference genome are represented in the evolving map, with an additional 50,000 clone fingerprints awaiting incorporation into the map assembly. Among these are repeat-rich and other clones that may well harbor genome rearrangements. Additional prioritization of sequencing targets will be undertaken when map construction and analysis of genome copy number alterations are complete.

Effect of Staphylococcus aureus and Streptococcus uberis on apoptosis of bovine mammary gland neutrophils in vitro

Neutrophils play an important role in the defence of the bovine mammary gland against bacterial infections. In the course of the resolution of mammary gland inflammation, neutrophils undergo programmed cell death &amp;ndash; apoptosis. The aim of this study was to confirm whether the co-cultivation of neutrophils of the bovine mammary gland with either Staphylococcus aureus or Streptococcus uberis leads to signs of apoptosis. In the study, 16 mammary glands of four virgin heifers aged 16 to 18 months were examined. Neutrophils were obtained by lavage after an induced influx. After a three-hour incubation of the neutrophils with bacteria in vitro, neutrophil apoptosis was detected by morphological features, by determination of histone-associated DNA fragments (ELISA), and by Annexin -V and propidium iodide positivity (flow cytometry). S. aureus and S. uberis reduced the incidence of karyopycnotic and zeiotic neutrophils (P &amp;lt; 0.01), and insignificantly reduced the concentration of histone -associated DNA fragments (P &amp;gt; 0.05). The incubation of neutrophils with bacteria, however, increased the proportion of Annexin &amp;ndash;V-positive cells (P &amp;lt; 0.01) and Annexin -V and propidium iodide-positive cells (P &amp;lt; 0.05). Co-cultivation of neutrophils with either S. aureus or S. uberis led to the induction of phosphatidylserine translocation characteristic of the early stage of apoptosis. The late signs of apoptosis were delayed by co-cultivation of neutrophils with both pathogens. Therefore it is obvious that although the programmed cell death of apoptosis is initiated by these pathogens, the completion of the program is delayed.

Translocation of Radionuclides of Co, Zn, Se, Rb, Y, Tc, and Re into Organs of Tomato Plant via Roots

The translocation of the radionuclides of Co, Zn, Se, Rb, Y, Tc, and Re into red and green fruits, flesh, seeds, rind, calyxes, flower, leaves, and stems via the root of the tomato plant at two different growth stages was studied by a multitracer technique. The contents (%/g) of Co, Zn, Se, and Y in the roots were the highest among the organs, but only small amounts of them were translocated into the aerial parts after 5 d cultivation with a multitracer. In contrast, Rb, Tc, and Re showed rapid translocation into the stems and leaves from the root. In the plants cultivated for 95 d with a multitracer, Zn, Se, and Rb distributed in all of the organs, Co in the organs except for flowers, and Y, Tc, and Re in the limited organs. The translocation ratio of the elements for the edible part of the plants cultivated for 95 d decreased in the order of Rb>Zn>Co approximately Se>Tc approximately Y>Re. The transfer factor of the elements for tomato fruit was determined to be in the range of 10(-5)-10(-2). The characteristic translocation behavior of the elements gives us fundamental information on the assessment of pollutant uptake by the tomato plant.

Reactive oxygen signaling and MAPK activation distinguish Epstein–Barr Virus (EBV)-positive versus EBV-negative Burkitt's lymphoma

Burkitt's lymphoma (BL) is an aggressive B cell neoplasm, which is one of the most common neoplasms of childhood. It is highly widespread in East Africa, where it appears in endemic form associated with Epstein-Barr virus (EBV) infection, and around the world in a sporadic form in which EBV infection is much less common. In addition to being the first human neoplasm to be associated with EBV, BL is associated with a characteristic translocation, in which the Ig promoter is translocated to constitutively activate the c-myc oncogene. Although many BLs respond well to chemotherapy, a significant fraction fails to respond to therapy, leading to death. In this article, we demonstrate that EBV-positive BL expresses high levels of activated mitogen-activated protein kinase and reactive oxygen species (ROS), and that ROS directly regulate NF-kappaB activation. EBV-negative BLs exhibit activation of phosphoinositol 3-kinase, but do not have elevated levels of ROS. Elevated reactive oxygen may play a role in diverse forms of viral carcinogenesis in humans, including cancers caused by EBV, hepatitis B, C, and human T cell lymphotropic virus. Our findings imply that inhibition of ROS may be useful in the treatment of EBV-induced neoplasia.

Proteomic Analysis of Acute Promyelocytic Leukemia Reveals That PML-RARalpha Induces Cell Cycle Progression and Mitotic Exit by Increased Expression and Decreased Ser63 Phosphorylation of OP18.

We applied a mass spectrometry based approach to explore the proteins differentially regulated by PML-RARalpha, a translocation characteristic of acute promyelocytic leukemia (APL). Bioinformatic pathway analysis placed the 46 identified PML-RARalpha regulated proteins into three major networks, OP18-MAPK1, HSP-STAT3 and CCT-MYC. Using this approach, we were able to generate a common cell cycle network of the proteins in these pathways. Further analysis indicated that mRNA expression of OP18, which belonged to this network, was elevated in APL patients and the increased OP18 protein expression upon PML-RARalpha induction was overcome by retinoic acid treatment. Here we also report, for the first time a novel role of PML-RARalpha in cell cycle progression and mitotic exit. RNA interference experiments revealed that siRNA against OP18 overcomes PML-RARalpha effects on cell cycle progression. In addition to increased OP18 expression by PML-RARalpha, 2D gel electrophoresis revealed an isomer of OP18, subsequently confirmed by 2D-western as ser63 phosphomer to be downregulated by PML-RARalpha. Based on these findings, point mutation experiments indicated that decreased phosphorylation of ser63 in OP18 is important for PML-RARalpha mediated cell cycle and mitotic index effects since a constitutive phosphorylated mutant (ser63/asp) of OP18 overcame the PML-RARalpha effects in U9/PR cells, NB4 and APL patients. In summary, our results demonstrate that the effect of PML-RARalpha on cell cycle progression and mitotic exit is via two mechanisms: increasing the expression of OP18 and decreasing the phosphorylation of OP18 at ser63.

Interphase Fluorescence In Situ Hybridization (FISH) with an IgH Probe Is Important in the Management of Patients with a Clinical Diagnosis of Chronic Lymphocytic Leukemia (CLL).

Genetic analysis has an increasing role in the diagnosis, classification, and management of patients with CLL. Although translocations involving the IgH locus are well characterized in B-cell malignancies such as follicular cell lymphoma, their frequency and significance in CLL are less well defined. We studied a series of patients with a clinical diagnosis of CLL using a FISH probe set including IgH.Methods: FISH was performed on blood using a DNA probe set designed to detect common chromosome anomalies associated with CLL and translocations involving IgH. Patients with an IgH abnormality were further studied using FISH probes sets for IgH and cyclin D1, BCL-2, BCL-3, BCL-6, BCL-11a, c-MYC, MALT-1, c-MAF, FGFR-3 or PAX-5. The clinical presentation, pathology, and flow cytometric immunophenotype was reviewed in patients with various translocations involving IgH.Results: Between 1/1/03 and 6/15/04, samples from 1032 patients with a clinical diagnosis of CLL were analyzed by FISH. Of these, 76 patients (7%) had translocations involving the IgH locus. Sixty one patients had a single translocation partner gene (cyclin D1 45%, BCL-2 24%, BCL-3 8%, c-MYC 2.5%, or BCL-11a 1.3%). Two patients had two independent clones (cyclin D1 and BCL-2; BCL-3 and BCL-11a). In 13 pts (17%) we could not identify the translocation partner. Thirty five (46%) of the 76 patients with IgH translocations had been seen at Mayo Clinic Rochester and had clinical and laboratory data for detailed review. Among these 35 patients, 16 (45%) had fusion of IgH and cyclin D1 and were diagnosed with mantle cell lymphoma (MCL). The immunophenotype of the monoclonal B cells was typical of MCL (CD5+, CD23-) in 6 patients and typical of CLL (CD5+, CD23+) in 4 patients. Six MCL patients had non-diagnostic immunophenotypes: CD5-, CD 23+ (n = 3) and CD5-, CD23- (n = 3). Twelve (34%) of the 35 patients had the IGH/BCL-2 fusion gene. Of these, 3 patients had leukemic phase follicular lymphoma, one had both CLL and MCL, and 8 had the diagnostic immunophenotype of CLL. The remaining 7 patients (19%) had a variety of translocation partners: BCL-3 (n = 1), BCL-3 and BCL-11a (n = 1), c-MYC (n = 2), and unknown (n = 3). The patients with a translocation involving BCL-3 had a typical CLL immunophenotype.Discussion: The IgH FISH probe detected a molecular defect in 7% of patients with a circulating monoclonal B cell population. In patients with a CLL immunophenotype, use of the IgH probe identified the IgH/cyclin D1 translocation characteristic of MCL in 4 patients, a finding of major clinical significance. Interestingly, after exclusion of MCL patients, more than 4% patients with CLL had other translocations involving IgH, a proportion comparable with other better defined chromosomal abnormalities in CLL. Although IgH/BCL-2 translocation is usually associated with follicular lymphoma, we identified 8 patients with CLL and this translocation. Translocations involving BCL-3 had been described before in CLL with an “atypical” immunophenotype. In contrast both of our patients with BCL-3 had typical phenotypes. Translocations involving IgH and BCL-11a have not been previously described. We conclude that FISH studies using the IgH probe improve the precision of diagnosis in CLL and could also have prognostic value.