MALIGNANT MYELOID TRANSFORMATION WITH ISOCHROMOSOME 7Q IN SHWACHMAN-DIAMOND-SYNDROME

Shwachman-Diamond syndrome is an autosomal recessive disorder characte rized by exocrine pancreatic dysfunction, bony metaphyseal dysostosis, various degrees of cytopenia, and a striking tendency to develop myel odysplastic syndrome and acute myeloblastic leukemia. Isochromosome 7 [i(7q)] is a rare non-random cytogenetic abnormality of myeloid cells in hematological malignancy. We report two cases of Shwachman-Diamond syndrome in which patients developed myelodysplastic syndrome and i(7q ), detected by G-banding karyotype analysis and fluorescence in situ h ybridization. Three other children have been previously reported to ha ve myelodysplastic syndrome in association with i(7q); two of them had Shwachman-Diamond syndrome. Isochromosome 7q may be a fairly specific marker of myeloid malignant transformation in this syndrome and play a role in its pathogenesis.