[Hematologic improvement of Pearson's syndrome confirmed by mitochondrial DNA analysis]

We report on an 8-month-old girl with Pearson's syndrome who presented with transfusion-dependent pancytopenia, exocrine pancreatic dysfunction, and lactic acidosis. Bone marrow findings were consistent with sideroblastic anemia and marked vacuolization of myeloid and erythroid precursors. Southern blot analysis of mitochondrial DNA (mtDNA) revealed a 4.5 kb deletion in peripheral blood cells. Gradual hematologic improvement was observed thereafter, and the patient was relieved of the need for blood transfusions. We were able to confirm a decrease of the mtDNA deletion in lymphocytes as well as in lymphoblastoid cell lines cultured from peripheral lymphocytes as the patient made steady hematologic progress.