RESUMO
BACKGROUND: Alpha thalassemia-myelodysplastic syndrome (ATMDS) is one of the possible complications related to the genetic instability typical of clonal hemopoietic disorders such as myelodysplastic syndromes (MDS). Hemoglobin H acquisition, which is hemoglobin without alpha chains and with 4 beta chains is the hallmark of this disease. OBSERVATION: An 86-year-old male with chronic, microcytic anemia was referred due to a fall in his hemoglobin level. The blood smear was remarkable for intense anisocytoses and poikilocytosis. Bone marrow analysis was followed by a diagnosis of MDS with a good prognostic score. Peripheral blood coloration with brilliant cresyl blue showed "golf ball-like" erythrocytes. Hemoglobin electrophoresis is notable for the presence of H hemoglobin. The new generation sequencing confirmed the diagnosis of ATMDS showing a non-sense mutation in the gene ATRX. CONCLUSION: The diagnosis of ATMDS should be considered in the presence of the association of MDS, microcytic anemia and marked blood smear abnormalities such as anisocytosis and poikilocytosis. A little less than 10% of all MDS are complicated by ATMDS.