ABSTRACT
Myelodysplastic syndrome is a group of stem cell disorder that is characterized by ineffective hematopoiesis and transformation to acute leukemia. Genetic analyses have an important role in establishing the diagnosis and determining the appropriate chemotherapy. Here a patient with myelodysplastic syndrome in whom isochromosome of long arm of chromosome 17 [i (17q)] cytogenetic abnormality was detected is presented and clinical findings in patients with this anomaly are discussed. Although i(17q) cytogenetic abnormality is a very rarely seen genetic change in patients with myelodysplastic syndrome, it is accepted as a poor prognostic criterion according to literature findings. Thus patients of myelodysplastic syndrom with this cytogenetic abnormality may be considered as a different clinical syndrome during the follow-up and treatment.