TET2 expression level and 5-hydroxymethylcytosine are decreased in refractory cytopenia of childhood.

Myelodysplastic syndromes (MDS) are myeloid malignancies characterized by ineffective hematopoiesis, dysplasia, peripheral cytopenia and increased risk of progression to acute myeloid leukemia. Refractory cytopenia of childhood (RCC) is the most common subtype of pediatric MDS and has overlapping clinical features with viral infections and autoimmune disorders. Mutations in TET2 gene are found in about 20-25% of adult MDS and are associated with a decrease in 5-hydroxymethylcytosine (5-hmC) content. TET2 deregulation and its malignant potential were reported in adult but not in pediatric MDS. We evaluated the gene expression and the presence of mutations in TET2 gene in 19 patients with RCC. TET2 expression level was correlated with 5-hmC amount in DNA and possible regulatory epigenetic mechanisms. One out of 19 pediatric patients with RCC was a carrier of a TET2 mutation. TET2 expression and 5-hmC levels were decreased in patients when compared to a disease-free group. Lower expression was not associated to the presence of mutation or with the status of promoter methylation, but a significant correlation with microRNA-22 expression was found. These findings suggested that TET2 downregulation and low levels of 5-hmC are inversely related to miR-22 expression. The existence of a regulatory loop between microRNA-22 and TET2 may play a role in MDS pathogenesis.

Acute myeloid leukemia of donor origin after allogeneic stem cell transplantation from a sibling who harbors germline XPD and XRCC3 homozygous polymorphisms.

A 54-year-old woman was diagnosed with infiltrative ductal breast carcinoma. Two years after treatment, the patient developed an acute myeloid leukemia (AML) which harbored del(11q23) in 8% of the blast cells. The patient was submitted for allogeneic stem cell transplantation (aSCT) from her HLA-compatible sister. Ten months after transplantation, she relapsed with an AML with basophilic maturation characterized by CD45(low) CD33(high), CD117⁺, CD13(-/+), HLA Dr(high), CD123(high), and CD203c⁺ blast cells lacking expression of CD7, CD10, CD34, CD15, CD14, CD56, CD36, CD64, and cytoplasmic tryptase. Karyotype analysis showed the emergence of a new clone with t(2;14) and FISH analysis indicated the presence of MLL gene rearrangement consistent with del(11q23). Interestingly, AML blast cell DNA tested with microsatellite markers showed the same pattern as the donor's, suggesting that this AML emerged from donor cells. Additionally, polymorphisms of the XPA, XPD, XRCC1, XRCC3 and RAD51 DNA repair genes revealed three unfavorable alleles with low DNA repair capacity.In summary, we report the first case of AML involving XPD and XRCC3 polymorphisms from donor origin following allogeneic stem cell transplantation and highlight the potential need for careful analysis of DNA repair gene polymorphisms in selecting candidate donors prior to allogeneic stem cell transplantation.

Efeitos adversos e resposta citogenética em pacientes com leucemia mieloide crônica tratados com imatinibe / Adverse events and cytogenetc response in patients with chronic myeloid leukemia treated with imatinib

A leucemia mieloide crônica (LMC) é uma doença mieloproliferativa clonal caracterizada citogeneticamente pelo cromossomo Philadelphia. Dentre as opções terapêuticas estão a hidroxiureia, o interferon-a, o transplante alogeneico de células-tronco hematopoéticas e o imatinibe. Esta última terapia tem demonstrado eficácia, principalmente na fase crônica da doença. Entretanto, alguns estudos têm demonstrado que alterações cromossômicas adicionais levam resistência à terapia, enquanto outros relatam aparecimento de manifestações clínicas indesejáveis, como cefaleia, náuseas e vômitos. Devido à importância desta terapia alvo-molecular, torna-se necessário analisar a resposta deste tratamento considerando a qualidade de vida dos pacientes. O objetivo deste trabalho foi analisar as manifestações clínicas indesejáveis e a resposta citogenética durante o tratamento com imatinibe em pacientes com LMC após uso prévio de interferon-a. O estudo clínico foi feito através de prontuários de 51 pacientes. A análise citogenética foi feita em células de medula óssea através da técnica de bandeamento GTG. As manifestações clínicas mais frequentes foram: cefaleia (37 por cento), náusea (37 por cento), vômito (33 por cento) e edema periférico (33 por cento). Esses sintomas foram considerados leves a moderados. Os pacientes que alcançaram resposta citogenética completa tiveram uma sobrevida significativamente maior que os pacientes que não apresentaram resposta citogenética ao tratamento (p=0.007). Oito pacientes sem resposta citogenética faleceram. Nossos resultados mostraram a importância do acompanhamento clínico (analisando o grau de tolerância medicamentosa) e citogenético, onde a presença de alterações cromossômicas adicionais mostrou um comportamento biológico distinto que não pode ser avaliado pelas técnicas moleculares. Desta forma, a análise citogenética representa uma importante ferramenta para o diagnóstico e monitoramento destes pacientes.

Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder characterized cytogenetically by the Philadelphia chromosome (Ph). Therapeutic options of this disease are: hydroxyurea, interferon-a, allogeneic HSCT and more recently imatinib. This latter therapy demonstrated efficacy in the treatment of CML, particularly in the chronic phase. However some studies have demonstrated that there are additional chromosomal alterations related to resistance while others have reported undesirable clinical manifestations during imatinib therapy such as headache, nausea and vomiting. Because of the importance of this new molecular target therapy, it may be necessary to analyze the response of this treatment in respect to the quality of life of patients. The aim of this study was to analyze the clinical manifestations and the cytogenetic response during imatinib therapy in fifty-one patients with CML who had previously been treated using interferon-a. Cytogenetic analysis was performed in bone marrow cells using GTG-banding. The commonest clinical manifestations were mild to moderate: headache (37 percent), nausea (37 percent), vomiting (33 percent) and edema (33 percent). Patients that achieved major cytogenetic response had a significantly longer median survival than patients without response (p=0.007). Eight patients evolved to death; none of them exhibited cytogenetic responses to imatinib. Our results show the importance of the clinical (analyzing the degree of tolerance to the drug) and cytogenetic follow-up, where the presence of additional chromosomal alterations showed a distinct biological pattern that is not identifiable by molecular techniques, and so cytogenetic analysis is an important tool for the diagnosis and monitoring of this group of patientss.

Estudo citogenético em síndrome mielodisplásica na infância / Cytogenetic study in myelodysplastica syndrome in childhood

A classificação, alterações citogenéticas e as peculiaridades da síndrome mielodisplásica na criança são apresentadas neste trabalho. Aspectos do tratamento aqui são comparados aos das síndromes mielodisplásicas nos adultos.

The classification, cytogenetic alterations and peculiarities of mielodisplastic syndrome in childhood are presented in this work, along with aspects of treatment in infancy compared withthose used in adults.