Functional polymorphisms of DNA repair genes in Latin America reinforces the heterogeneity of Myelodysplastic Syndrome.

Nucleotide excision repair pathway (NER) is an essential mechanism for single-strand breaks (SSB) repair while xeroderma pigmentosum family (XPA to XPG) is the most important system to NER. Myelodysplastic syndrome (MDS) is a heterogeneous hematological cancer characterized by cytopenias and risk of acute myeloid leukemia (AML) transformation. MDS pathogenesis has been associated with problems of DNA repair system. This report aimed to evaluate NER polymorphisms (XPA rs1800975, XPC rs2228000, XPD rs1799793 and XPF rs1800067) in 269 MDS patients of different populations in Latin America (173 Brazilian and 96 Argentinean). Genotypes were identified in DNA samples by RT-qPCR using TaqMan SNP Genotyping Assay. Regarding rs1799793 polymorphism of XPD for Brazilian population, the heterozygous genotype AG presented a high odds ratio (OR) to have a normal karyotype (p = 0.012, OR=3.000) and the mutant homozygous genotype AA was associated to a high OR of AML transformation (p = 0.034, OR=7.4). In Argentine population, the homozygous mutant AA genotype of rs1800975 polymorphism of XPA was associated with an increased odd to have hemoglobin levels below 8g/dL (p = 0.013, OR=10.000) while for the rs1799793 polymorphism of XPD, the heterozygous AG genotype decreased OR to be classified as good (p < 0.001, OR=9.05 × 10-10), and intermediate (p < 0.001, OR=3.08 × 10-10), according to Revised-International Prognostic Scoring System. Regarding the rs1800067 polymorphisms of XPF, the homozygous mutant AA genotype showed a decreased OR to be classified as good (p < 0.001, OR=4.03 × 10-13) and intermediate (p < 0.001, OR=2.54 × 10-13). Our report reinforces the heterogeneity of MDS and demonstrates the importance of ethnic differences and regional influences in pathogenesis and prognosis of MDS.

Functional polymorphisms of DNA repair genes in Latin America reinforces the heterogeneity of Myelodysplastic Syndrome

Abstract Nucleotide excision repair pathway (NER) is an essential mechanism for single-strand breaks (SSB) repair while xeroderma pigmentosum family (XPA to XPG) is the most important system to NER. Myelodysplastic syndrome (MDS) is a heterogeneous hematological cancer characterized by cytopenias and risk of acute myeloid leukemia (AML) transformation. MDS pathogenesis has been associated with problems of DNA repair system. This report aimed to evaluate NER polymorphisms (XPA rs1800975, XPC rs2228000, XPD rs1799793 and XPF rs1800067) in 269 MDS patients of different populations in Latin America (173 Brazilian and 96 Argentinean). Genotypes were identified in DNA samples by RT-qPCR using TaqMan SNP Genotyping Assay. Regarding rs1799793 polymorphism of XPD for Brazilian population, the heterozygous genotype AG presented a high odds ratio (OR) to have a normal karyotype (p= 0.012, OR=3.000) and the mutant homozygous genotype AA was associated to a high OR of AML transformation (p= 0.034, OR=7.4). In Argentine population, the homozygous mutant AA genotype of rs1800975 polymorphism of XPA was associated with an increased odd to have hemoglobin levels below 8g/dL (p= 0.013, OR=10.000) while for the rs1799793 polymorphism of XPD, the heterozygous AG genotype decreased OR to be classified as good (p< 0.001, OR=9.05 × 10−10), and intermediate (p< 0.001, OR=3.08 × 10−10), according to Revised-International Prognostic Scoring System. Regarding the rs1800067 polymorphisms of XPF, the homozygous mutant AA genotype showed a decreased OR to be classified as good (p< 0.001, OR=4.03 × 10−13) and intermediate (p< 0.001, OR=2.54 × 10−13). Our report reinforces the heterogeneity of MDS and demonstrates the importance of ethnic differences and regional influences in pathogenesis and prognosis of MDS.

Clasificaciones y sistemas pronósticos en síndromes mielodisplásicos / Classification and prognostic systems in myelodysplastic syndromes

Myelodysplastic syndrome (MDS) comprises a group of heterogeneous hematological disorders with risk of leukaemic evolution (LE), characterized by varied degrees of peripheral cytopenias related to a progressive bone marrow (BM) failure. Due to the heterogeneity of this pathology and the difficulty to make decisions regarding therapy, different classification and prognostic systems have been developed. The French-AmericanBritish cooperative group defined the first criterion for a systematic classification in 1982 that recognized morphologic entities: refractory anemia (RA), RA with ringed sideroblasts (RARS), RA with excess of blast (RAEB), RAEB in transformation (RAEBt) and chronic myelomonocytic leukemia (CMML). Although the FAB is the classification with major agreement, it has some prognostic failures. Therefore, since 1985 different instruments-scoring systems for prognosis were developed taking into account diverse clinical parameters including the cytogenetic analysis in 1993. In order to standardize prognostic features in MDS the International Scoring System (IPSS) was generated in 1997. This score defined risk groups for survival and LE on the basis of percentage of BM myeloblasts, cytogenetic abnormalities and number of cytopenias. Finally in 1999, the World Health Organization proposed a new classification system based on morphology and cytogenetic findings making another intent to sort out the heterogeneity of this pathology

Los síndromes mielodisplásicos comprenden un grupo heterogéneo de trastornos ematológicos caracterizados por grados variables de citopenias periféricas relacionadas con una falla medular progresiva con riesgo de evolución leucémica. Dada la heterogeneidad de la patología y la dificultad de aplicar una terapéutica eficaz, se han publicado diversos sistemas de clasificación y pronóstico. El primer criterio de clasificación sistemática fue definido en 1982 por el Grupo Cooperativo FrancoAmericano-Británico (FAB) reconociendo entidades morfológicas: anemia refractaria (AR), AR con sideroblastos anillados (ARSA), AR con exceso de blastos (AREB), AREB en transformación (AREBt), y leucemia mielomonocítica crónica (LMMC). Aunque es la clasificación de mayor reconocimiento internacional, posee ciertas falencias pronósticas. Consecuentemente, desde 1985 se registran diferentes sistemas de predicción que toman en cuenta ciertas variables clínicas e incorporan, en 1993, el estudio citogenético. Finalmente, en 1997 se genera el Sistema Pronóstico Internacional (IPSS), el cual discrimina grupos de riesgo para supervivencia y evolución leucémica teniendo en cuenta el porcentaje de blastos en médula ósea, el cariotipo y las citopenias periféricas. El último abordaje sugerido por la Organización Mundial de la Salud, en 1999, propone un nuevo sistema de clasificación basado en hallazgos morfológicos y citogenéticos para entender esta compleja patología.