Small RNA Profiling in an HTLV-1-Infected Patient with Acute Adult T-Cell Leukemia-Lymphoma at Diagnosis and after Maintenance Therapy: A Case Study.

Small RNAs (sRNAs) are epigenetic regulators of essential biological processes associated with the development and progression of leukemias, including adult T-cell leukemia/lymphoma (ATLL) caused by human T-cell lymphotropic virus type 1 (HTLV-1), an oncogenic human retrovirus originally discovered in a patient with adult T-cell leukemia/lymphoma. Here, we describe the sRNA profile of a 30-year-old woman with ATLL at the time of diagnosis and after maintenance therapy with the aim of correlating expression levels with response to therapy.

Role of miRNAs in Human T Cell Leukemia Virus Type 1 Induced T Cell Leukemia: A Literature Review and Bioinformatics Approach.

Human T cell leukemia virus type 1 (HTLV-1) was identified as the first pathogenic human retrovirus and is estimated to infect 5 to 10 million individuals worldwide. Unlike other retroviruses, there is no effective therapy to prevent the onset of the most alarming diseases caused by HTLV-1, and the more severe cases manifest as the malignant phenotype of adult T cell leukemia (ATL). MicroRNA (miRNA) dysfunction is a common feature of leukemogenesis, and it is no different in ATL cases. Therefore, we sought to analyze studies that reported deregulated miRNA expression in HTLV-1 infected cells and patients' samples to understand how this deregulation could induce malignancy. Through in silico analysis, we identified 12 miRNAs that stood out in the prediction of targets, and we performed functional annotation of the genes linked to these 12 miRNAs that appeared to have a major biological interaction. A total of 90 genes were enriched in 14 KEGG pathways with significant values, including TP53, WNT, MAPK, TGF-ß, and Ras signaling pathways. These miRNAs and gene interactions are discussed in further detail for elucidation of how they may act as probable drivers for ATL onset, and while our data provide solid starting points for comprehension of miRNAs' roles in HTLV-1 infection, continuous effort in oncologic research is still needed to improve our understanding of HTLV-1 induced leukemia.

HLA-B*35 as a new marker for susceptibility to human T-cell lymphotropic virus type 1 (HTLV-1) Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) in patients living in Argentina.

BACKGROUND: Human T-cell lymphotropic virus type 1 (HTLV-1) is the etiological agent of HTLV associated myelopathy/ Tropical Spastic Paraparesis (HAM/TSP) and Adult T cell leukemia/lymphoma (ATLL), in around 2-5% of the infected individuals. Host genetic background might play a role in disease progression. Several previous studies across many countries report HLA haplotype to be one such factor. Here, we sequenced HLA-A, -B and -C of 66 individuals by Sequence-Based Typing (SBT), and compared the frequency of different alleles among ATLL patients, HAM/TSP patients, asymptomatic carriers and non-infected individuals living in Argentina. RESULTS: The frequency of HLA-A, -B and -C alleles largely matched that of the general population in Argentina. We identified HLA-A*02, HLA-B*35 and HLA-C*07 as associated to protection from ATLL (p = 0.031), susceptibility to HAM/TSP (p < 0.001) and susceptibility to ATLL (p = 0.017), respectively. We also found a strong correlation between high proviral load (PVL) and disease (p = 0.008), but were unable to identify any particular allele associated with high or low PVL. CONCLUSIONS: We have found HLA-A*02, HLA-B*35 and HLA-C*07 to be associated to protection from ATLL (HLA-A*02) and susceptibility to HAM/TSP (HLA-B*35) or to ATLL (HLA-C*07), respectively. Whereas HLA-A*02 protection from ATLL has already been extensively described in other regions of the world, this is the first report that links HLA-B*35 and an increased susceptibility to HAM/TSP. As for HLA-C*07 it has previously been associated to susceptibility to HAM/TSP in other countries but in our population it has been linked to ATLL.

Low genetic diversity of the Human T-cell Lymphotropic Virus (HTLV-1) in an endemic area of the Brazilian Amazon basin.

The Human T-cell Lymphotropic Virus (HTLV-1) is a Deltaretrovírus that was first isolated in the 1970s, and associated with Adult T-cell Leucemia-Lymphoma (ATLL), and subsequently to Tropical Spastic Paraparesis-Myelopathy (TSP/HAM). The genetic diversity of the virus varies among geographic regions, although its mutation rate is very low (approximately 1% per thousand years) in comparison with other viruses. The present study determined the genetic diversity of HTLV-1 in the metropolitan region of Belém, in northern Brazil. Blood samples were obtained from patients at the UFPA Tropical Medicine Nucleus between January 2010 and December 2013. The DNA was extracted and the PX region of the HTLV was amplified using nested PCR. The positive samples were then digested using the Taq1 enzyme for the identification and differentiation of the HTLV-1 and HTLV-2. The 5'LTR region of the positive HTLV-1 samples were amplified by nested PCR, and then sequenced genetically. The phylogenetic analysis of the samples was based on the maximum likelihood method and the evolutionary profile was analyzed by the Bayesian approach. Overall, 78 samples tested positive for HTLV-1, and 44 were analyzed here. The aA (cosmopolitan-transcontinental) subtype was recorded in all the samples. The following evolutionary rates were recorded for the different subtypes-a: 2.10-3, b: 2.69. 10-2, c: 6.23. 10-2, d: 3.08. 10-2, e: 6. 10-2, f: 1.78. 10-3, g: 2.2. 10-2 mutations per site per year. The positive HTLV-1 samples tested in the present study were characterized by their low genetic diversity and high degree of stability.

Microsatellite alterations are also present in the less aggressive types of adult T-cell leukemia-lymphoma.

BACKGROUND: Adult T-cell leukemia/lymphoma (ATL) is a mature T-cell neoplasia etiologically linked to HTLV-1. Manifestations of ATL are diverse and different clinical types with different tissue involvement and aggressiveness have been described. The mechanisms that lead to the development of ATL clinical types have not yet been clarified. Considering that in ATL patients HTLV-1 infection generally occurs in childhood, a multistep carcinogenesis model has been proposed. Microsatellite alterations are important genetic events in cancer development and these alterations have been reported in the aggressive types of ATL. Little is known about oncogenesis of the less aggressive types. METHODOLOGY/PRINCIPAL FINDINGS: In this study we investigated the role of the microsatellite alterations in the pathogenesis mediated by HTLV-1 in the different types of ATL. We examined the presence of microsatellite instability (MSI) and loss of heterozigosity (LOH) in matched pair samples (tumoral and normal) of 24 patients with less aggressive types (smoldering and chronic) and in aggressive types (acute and lymphoma) of ATL. Four microsatellite markers D10S190, D10S191, D1391 and DCC were analyzed. MSI was found in four patients, three smoldering and one chronic, and LOH in four patients, three smoldering and one acute. None of the smoldering patients with microsatellite alterations progressed to aggressive ATL. CONCLUSIONS/SIGNIFICANCE: To our knowledge, this is the first report describing the presence of MSI and LOH in the less aggressive types of ATL. These results indicate that microsatellite alterations may participate in the development of the less aggressive types of ATL.

[Using epidemiology and bioinformatics for studying HTLV-1 infection-associated adult T-cell leukemia]. / Epidemiología y bioinformática en el estudio de la Leucemia Linfoma de Células T del Adulto asociada a la infección con VLHT-1.

OBJECTIVES: Establishing a correlation between the number of HTLV-1 provirus and the characteristics of the genomic environment in ATL cases. METHODOLOGY: A systematic search was made of publications as well as a meta-analysis of the pertinent literature considering proviruses per chromosome and structural and functional characteristics of flanking chromatin regions as variables. The concordance of experts' study was evaluated by Spearman Rho correlation. Publication bias was analysed by funnel plot and the Egger statisgrapher. A fixed effects model was applied according to heterogeneity evaluation to combine the results of integration occurring in coding sequences as well as coding sequences according to their molecular function. RESULTS: The expert concepts' Kappa index was 0.7 and no publication bias was observed. The meta-analysis result was homogeneous (p>0.05). HTLV-1 integration was directed towards several chromosomes' telomeric and subtelomeric regions. The combination of published results in the articles which were analysed supported the hypothesis of integration events being site-directed towards coding regions of the human genome (p<0.05). Moreover, the groups of genes having enzymatic and receptor functions was statistically significant. CONCLUSION: The results led to concluding that HTLV-I integration in the ATLL cases analysed here was not random but was directed towards regulatory regions. Such results could help to explain the role of some processes involved in leukemogenesis.

Epidemiología y bioinformática en el estudio de la Leucemia Linfoma de Células T del Adulto asociada a la infección con VLHT-1 / Using epidemiology and bioinformatics for studying HTLV-1 infection-associated adult T-cell leukemia

Objetivos Establecer la relación entre el número de provirus VLHT-1 y las características de la cromatina adyacente en casos de Leucemia Linfoma de Células T del Adulto. Metodología Se realizó una revisión sistemática y un metaanálisis de la literatura publica que considero como variables de estudio los provirus por cromosoma y características estructurales y funcionales de la cromatina adyacente a los sitios de integración. La concordancia entre los resultados de la evaluación que emitieron dos expertos fue evaluada con el coeficiente de Spearman Rho. Se evaluó el sesgo de publicación mediante el gráfico de embudo y el estadígrafo Egger. De acuerdo con los resultados de la evaluación de la heterogeneidad se aplicó el modelo de efectos fijos para la combinación de los resultados de las integraciones que ocurrieron en: secuencias codificantes y secuencias codificantes de acuerdo con su función molecular. Resultados La concordancia entre expertos evaluadores fue de 0,7. No se encontró sesgo de publicación. Se determinó homogeneidad entre los estudios seleccionados (p>0,05). El provirus VLHT-1 se integró en secuencias en regiones teloméricas y subteloméricas. La combinación de los resultados mostró una integración sitio dirigida hacia regiones codificantes del genoma humano (p<0,05). Conclusión En su conjunto los resultados permiten concluir que la integración proviral no es al azar en LCCTA; ésta ocurrió en regiones reguladoras o de control; que explicarían algunos de los proceso moleculares involucrado en leukomogénesis.

Objectives Establishing a correlation between the number of HTLV-1 provirus and the characteristics of the genomic environment in ATL cases. Methodology A systematic search was made of publications as well as a meta-analysis of the pertinent literature considering proviruses per chromosome and structural and functional characteristics of flanking chromatin regions as variables. The concordance of experts' study was evaluated by Spearman Rho correlation. Publication bias was analysed by funnel plot and the Egger statisgrapher. A fixed effects model was applied according to heterogeneity evaluation to combine the results of integration occurring in coding sequences as well as coding sequences according to their molecular function. Results The expert concepts' Kappa index was 0.7 and no publication bias was observed. The meta-analysis result was homogeneous (p>0.05). HTLV-1 integration was directed towards several chromosomes' telomeric and subtelomeric regions. The combination of published results in the articles which were analysed supported the hypothesis of integration events being site-directed towards coding regions of the human genome (p<0.05). Moreover, the groups of genes having enzymatic and receptor functions was statistically significant. Conclusion The results led to concluding that HTLV-I integration in the ATLL cases analysed here was not random but was directed towards regulatory regions. Such results could help to explain the role of some processes involved in leukemogenesis.

Common genetic variants and risk for non-Hodgkin lymphoma and adult T-cell lymphoma/leukemia in Jamaica.

We evaluated whether risk of non-Hodgkin lymphoma (NHL), particularly adult T-cell leukemia/lymphoma (ATL) related to human T-lymphotropic virus (HTLV) infection was associated with 63 single nucleotide polymorphisms (SNPs) from 38 candidate genes. The 395 NHL cases registered in Jamaica were matched by age, sex, calendar-year and HTLV serostatus to 309 controls from the same population. Interleukin 13 (IL13) Ex4+98A>G SNP (rs20541) was associated with decreased NHL risk (OR(AG/AA) = 0.62,95% CI = 0.44-0.87, p = 0.006), as was vascular cell adhesion molecule-1, VCAM1 Ex9+149G>A SNP (rs1041163) (OR(CT) = 0.77, 95% CI = 0.54-1.10, OR(CC) = 0.35, 95% CI = 0.16-0.76, p-trend = 0.007). Both results were stronger in analyses restricted to ATL cases and HTLV-positive controls, suggesting a role for these genes in ATL etiology (IL13 OR(AG/AA) = 0.54, 95% CI = 0.36-0.84, p = 0.005; VCAM1 OR(CT) = 0.65, 95% CI = 0.42-1.01, OR(CC) = 0.20, 95% CI = 0.08-0.54, p-trend = 0.001). Confirmation of these results in Caribbean and other populations is needed.

Identification of clonally rearranged T-cell receptor beta chain genes in HTLV-I carriers as a potential instrument for early detection of neoplasia.

We analyzed the genetic recombination pattern of the T-cell receptor beta-chain gene (TCR-beta) in order to identify clonal expansion of T-lymphocytes in 17 human T-lymphotropic virus type I (HTLV-I)-positive healthy carriers, 7 of them with abnormal features in the peripheral blood lymphocytes. Monoclonal or oligoclonal expansion of T-cells was detected in 5 of 7 HTLV-I-positive patients with abnormal lymphocytes and unconfirmed diagnosis by using PCR amplification of segments of TCR-beta gene, in a set of reactions that target 102 different variable (V) segments, covering all members of the 24 V families available in the gene bank, including the more recently identified segments of the Vbeta-5 and Vbeta-8 family and the two diversity beta segments. Southern blots, the gold standard method to detect T-lymphocyte clonality, were negative for all of these 7 patients, what highlights the low sensitivity of this method that requires a large amount of very high quality DNA. To evaluate the performance of PCR in the detection of clonality we also analyzed 18 leukemia patients, all of whom tested positive. Clonal expansion was not detected in any of the negative controls or healthy carriers without abnormal lymphocytes. In conclusion, PCR amplification of segments of rearranged TCR-beta is reliable and highly suitable for the detection of small populations of clonal T-cells in asymptomatic HTLV-I carriers who present abnormal peripheral blood lymphocytes providing an additional instrument for following up these patients with potentially higher risk of leukemia.

Adult T-cell leukemia/lymphoma in Jujuy, north-west Argentina.

Human T-cell leukemia virus type 1 (HTLV-1) infection is prevalent in native Americans living in the Andes. Some of their malignant lymphomas (ML) show a peculiar histology suggestive of adult T-cell leukemia/lymphoma (ATLL). To determine whether ML resembling ATLL are indeed ATLL, re-analysis of 34 cases occurring in Jujuy, a province of Argentina, was conducted, concentrating on immunological phenotype, integration of HTLV-1 proviral DNA, expression of HTLV-1 p40Tax and p27Rex, and infection of Epstein-Barr virus (EBV). The ML were 22 cases of mature peripheral T-cell and natural killer (NK)-cell neoplasm (mT/NKN), 11 B-cell malignant neoplasms and one Hodgkin's lymphoma. Polymerase chain reaction against the HTLV-1 proviral DNA, using DNA extracted from paraffin sections, indicated integration of the HTLV-1 proviral DNA in three cases of eight mT/NKN. Two other cases of mT/NKN were positive for anti-HTLV-1 antibodies. Expression of p40Tax and p27Rex was detected in all five of these mT/NKN cases associated with HTLV-1. As such, these five mT/NKN were rediagnosed as ATLL. In situ hybridization signals for EBV-encoded small nuclear early region-1 were detected in nine cases of mT/NKN, of which five cases of NK-cell lymphoma were found to have cytoplasmic CD3 expression, a CD56 phenotype and positivity of TIA1. According to the new World Health Organization classification, the mT/NKN class includes five cases of ATLL and five cases of NK-cell lymphomas. The five cases of ATLL were of native American extraction from an HTLV-1-endemic area around Jujuy, north-west Argentina.

Genetic mutation and early onset of T-cell leukemia in pediatric patients infected at birth with HTLV-I.

T-cell leukemia/lymphoma (T-c LL) associated with prior infection with HTLV-I is rarely described in children. We present herein, the clinical, morphological, and virologic features of T-c LL, which occurred in eight pediatric cases with similar features of ATLL described in adults. There were three girls and five boys with age ranging from 2 to 18 years. Lymphoadenopathy, hepatosplenomegaly and marked skin lesions were presented in all cases. Five patients had hypercalcemia. The diagnostic criteria of T-c LL were based on both morphological and immunophenotypical analyses characterized by T-cell markers positively. Seven cases were cCD3+, CD4/CD25+, whereas CD1a and TdT were negative in all cases tested. HTLV-I antibodies were detected in all cases. HTLV-I provirus integration of at least one provirus was seen in all cases tested by molecular analysis. Mother-to-child transmission of HTLV-I was demonstrated in six cases. Interestingly, a homozygous deletion in p16 gene locus was observed in all four cases studied, while exons 7 and 8 of p53 were deleted in one child. The deletion of the p16(INK4A)/p14(ARF) or mutation of p53, key regulatory protein of cell cycle checkpoint in G1/S progression, found in five of the eight pediatric patients suggests that in these cases genetic lesions associated with HTLV-I infection may predispose for an early onset of leukemia.

The methylenetetrahydrofolate reductase C677T gene polymorphism decreases the risk of childhood acute lymphocytic leukaemia.

We have determined the prevalence of methylenetetrahydrofolate reductase (MTHFR) mutations C677T and A1298C in 71 children (< or = 15 years) with acute lymphoblastic leukaemia (ALL) and in 71 control subjects. Odds ratio (OR) for ALL linked to MTHFR C677T was 0.4 (95% CI 0.2-0.8); for heterozygotes it was 0.5 (95% CI 0.2-0.9) and for homozygotes it was 0.3 (95%CI 0.09-0.8). MTHFR A1298C yielded an overall OR for ALL of 1.3 (95% CI: 0.7-2.6); for heterozygotes it was 1.3 (95% CI: 0.7-7.6) and for homozygotes it was 2.8 (95% CI 0.5-15.6). In conclusion, MTHFR C677T was linked to a significant 2.4-fold decreased risk of developing childhood ALL, whereas MTHFR A1298C did not significantly affect the risk of ALL in our population.

TEL-AML1 fusion gene frequency in paediatric acute lymphoblastic leukaemia in Brazil.

We analysed 67 samples from Brazilian children of diverse ethnic origins with acute lymphoblastic leukaemia (ALL) for the presence of the TEL-AML1 fusion gene transcripts using reverse transcription polymerase chain reaction (RT-PCR). All 12 positive cases (20% of the 60 B-cell precursor ALL) had common (CD10+) ALL with a mean age of 4 years (range 1-10 years). We conclude that the frequency, age, distribution and clinical features of the TEL-AML1 fusion gene-positive ALL is similar in the diverse ethnic backgrounds of the Brazilian children to that in other countries with predominantly white Caucasian or oriental ethnicity. Apparent exceptions to this generality are discussed.

The first report of familial adult T-cell leukemia/lymphoma in Argentina.

Here we describe two Caucasian brothers who developed adult T-cell leukemia/lymphoma (ATLL), within a short period of time. These two patients have never left Argentina. Their parents are dead and according to the family history it is possible that the mother may have been affected by spastic paraparesis. The daughters reported that their mother had suffered from increasing difficulty in walking for many years which finally made it impossible for to her walk. There are no other data to support the presumptive diagnosis. One of the patients presented with acute disease while the other had a lymphoma type disorder. Both were positive for HTLV 1. The first patient died with disease progression ten months after diagnosis and the second is in partial remission 13 months after diagnosis. Immunophenotyping showed CD4+, CD5+, CD3+, CD2+, CD8 (-). Two asymptomatic brothers with positive HTLV 1 serology were detected. This is the first family case that has been reported in Argentina.

[Adult T cell leukemia lymphoma in Chile. A clinical pathologic and molecular study of 26 patients]. / Leucemia linfoma T del adulto en Chile. Estudio clínico-patológico y molecular de 26 pacientes.

BACKGROUND: Adult T cell leukemia lymphoma is a lymphoproliferative syndrome etiologically associated to human T cell lymphotropic virus type I. AIM: To describe the clinical and laboratory features of 26 Caucasian Chilean patients, with HTLV-I positive adult T-cell leukemia lymphoma (ATLL). MATERIAL AND METHODS: Diagnostic criteria included clinical features, cell morphology, immunophenotype, HTLV-I serology and/or DNA analysis by Southern blot or PCR. RESULTS: According to the clinical presentation, 12 cases had the acute ATLL form, 6 had a lymphoma, 4 the chronic form and 4 had smoldering ATLL. The median presentation age was 50 years, younger than the Japanese patients, but significantly older than patients from other South American countries (e.g. Brasil, Jamaica, Colombia). The main clinical features: lymphadenopathy, skin lesions and hepatosplenomegaly, were similar in frequency to those of patients from other countries, except for the high incidence of associated neurological disease. Tropical Spastic Paraparesis (TSP) in our series of ATLL, was seen in one third of the patients (8/26). A T-cell immunophenotype was shown in all 26 cases and HTLV-I serology was positive in 25/26 patients. Molecular analysis on the seronegative patient showed clonal integration of proviral HTLV-I DNA into the lymphocytes DNA, and thus he may have been a poor responder to the retroviral infection. Proviral DNA integration was also demonstrated in 15/16 patients being clonal in 10, polyclonal in 3 (all smoldering cases) and oligoclonal in one. CONCLUSIONS: ATLL in Chile has similar clinical and laboratory features than the disease in other parts of the world, except for a younger age than Japanese patients but older than those from other Latin American countries and a high incidence of patients with associated TSP. Detailed morphological and immunophenotypic analysis of the abnormal circulating lymphocytes, together with the documentation of HTLV-I by serology and/or DNA analysis are key tests for the identification of this disease.

Human leukocyte antigen class II alleles associated with human T cell lymphotropic virus type I infection and adult T-vell leukemia/lymphoma in a black population

BACKGROUND: Human T-cell lymphotropic virus type I (HTLV-I) is linked to adult T-cell luekemia/lymphoma (ATL) and HTLV-I associated myelopathy (HAM; also known as tropical spastic paraparesis [TSP]), a chronic neurodegenerative disorder. Worldwide, several million HTLV-I carriers are at risk for disease, with an estimated lifetime cumulative risk of 1 percent-5 percent. However, the determinants of disease progression are relatively unknown. We studied human leukocyte antigens (HLA class II) that have been implicated in the pathogenesis of HTLV-I related diseases. METHODS: We analyzed HLA class II alleles among asymptomatic HTLV-I carriers (n = 45), patients with ATL (n = 49) or HAM/TSP (n = 54), and HTLV-I seronegative control subjects (n = 51). All participants were of African descent and were enrolled in epidemiologic studies conducted at the University of the West Indies, Kingston, Jamaica. We used standard microlymphocytotoxicity assays for HLA antigen serotyping and polymerase chain reaction-based methods to examine HLA class II DRB1 and DQB1 alleles. RESULTS: Two antigens determined by serotyping DR15 and DQ1, occurred at significantly increased frequency among HTLV-I carriers compared with seronegative control subjects (42 percent versus 22 percent for DR15 [odds ratio [OR] = 2.7; 95 percent confidence interval [CI] - 1.0-7.2] and 78 percent versus 53 percent for DQ1 [OR = 3.1; 95 percent CI= 1.2-8.5]). Asymptomatic carriers were shown to have and HLA class II allele distribution similar to that of patients with ATL, and the frequencies of the alleles DRB1*1501, DRB1*1101, and DQB1*0602 were significantly increased among patients with ATL compared with patients with HAM/TSP. CONCLUSIONS: These data suggest that host genetic background is an important factor in determining weather HTLV-I carriers develop either ATL or HAM/TSP.(AU)

T-cell receptor J beta 1/J beta 2 locus rearrangements in an HTLV-1-positive T-cell lymphoma with complex chromosomal aberrations.

We report a case of human T-cell lymphotropic virus type 1 (HTLV-1)-infected adult T-cell lymphoma that has multiple chromosomal abnormalities, including the presence of an additional 7q22-36, which contains the locus of the T-cell receptor (TCR) beta chain gene. Specific TCR J beta 1/J beta 2 gene rearrangements were detected in both marrow and peripheral blood DNA, with evidence of further evolution of the transformed clonal population within the peripheral lymphocytes. To our knowledge, this is the first case in which gene rearrangements have been associated with additional TCR loci. Consequently, it is advised that every effort should be made to correlate chromosomal abnormalities with gene rearrangement by molecular methods.

Translocation 11;14 in three children with acute lymphoblastic leukemia of T-cell origin.

Clinical, karyotypic, immunophenotypic, and molecular profiles of three TALL cases carrying a t(11;14) are discussed and compared with data in the literature. As previously reported, t(11;14)(p13;q11) was associated in one patient with a TALL profile of intermediate stage of maturation (CD7+, CD4+, CD8+). However, the same translocation was found to be present in another patient with a more immature, pro-TALL profile (CD7+, CD4-, CD8-). Both patients showed molecular rearrangements of the TCR beta chain gene. A third patient, with a very immature pro-TALL profile (CD34+, CD7+, CD4-, CD8-), carrying a t(11;14)(p15;q11), showed molecular rearrangements of the TCR beta and gamma chain genes, while the IgH chain genes were in germline configuration. Our data indicate that t(11;14) can also be present in TALLs of more immature stages of intrathymic development; the significant factor determining the clinical behavior of TALLs is apparently related more to cell differentiation than to the presence of this chromosome rearrangement.