ABSTRACT. The myelodysplastic syndromes (MDS) are clonal hematopoietic diseases characterized by medullary dysplasia, cytopenias, and frequent evolution to acute myeloid leukemia. In 1982, the French-American-British (FAB) group proposed a classification for the MDS, based on morphological characteristics of peripheral blood and of the bone marrow. Later, cytogenetics proved to be a useful tool for the refinement of prognosis, through the use of the International Prognosis Score System (IPSS), as well as through evidence of clonality. Recently, the World Health Organization (WHO) proposed a new classification for the MDS, based on significant modifications of the FAB proposal, with the inclusion of chromosome analysis. A cytogenetic analysis was made of 17 patients with symptoms of MDS in the State of Pará, based on WHO recommendations, and application of the IPSS. Good metaphases were obtained for 13 patients; 12 had a normal karyotype and only one had a clonal abnormality, del(3)(p25). The genes related to neoplastic processes that have been mapped to 3p are: XPC in 3p25.1 and FANCD2 and VHL in 3p25-26. Four patients had classic symptoms of MDS; in the rest the possibility of MDS was excluded or several months of observation before diagnosis were recommended. Among those with MDS, it was not possible to apply IPSS and WHO recommendations, because fundamental data were lacking, specifically the medullary blast and ring sideroblast counts. We advocate the implementation of routine cytogenetic analyses for the study of MDS, especially in patients with moderate hematopoietic dysplasia.

Key words: Myelodysplastic syndromes, Cytogenetics, Classification, del(3)(p25)