RESUMEN
Among the etiologies of anemia in the newborn, those related to mitochondrial cytopathies are rare. Pearson syndrome is mostly diagnosed during infancy and characterized by refractory sideroblastic anemia with vacuolization of marrow progenitor cells and exocrine pancreatic dysfunction. We describe two diagnosed cases of Pearson syndrome in the early neonatal period caused by severe macrocytic aregenerative anemia. Bone marrow aspiration revealed sideroblastic anemia and vacuolization of erythroblastic precursors. The diagnosis was confirmed by genetic analysis revealing a deletion in the mitochondrial DNA. These two newborns received monthly transfusions. Five other newborns suffering from Pearson syndrome with various clinical symptoms were found in literature. Pearson syndrome, rarely diagnosed in newborns, should be suspected in the presence of macrocytic aregenerative anemia and requires a bone marrow aspirate followed by a genetic analysis from a blood sample.