DNA double-strand breaks were quantified by γH2AX-foci in CD34+ peripheral blood cells, and telomere length was measured by flow-FISH.<h4>Results</h4>Elevated serum ferritin was associated with increased cytogenetic abnormalities and somatic mutations at genomic regions commonly involved in MDS, higher levels of double-strand breaks, and shortened telomeres in granulocytes but not in lymphocytes. The gene discussed is CD34; the disease is myelodysplastic syndrome.