Correlation of cytogenetic findings with clinical features in 18 patients with inv(3)(q21q26) or t(3;3)(q21;q26).

An inversion in the long arm of chromosome 3--inv(3)(q21q26)--or a translocation between both homologous chromosomes 3--t(3;3)(q21;q26)--is found specifically in myeloid neoplasias characterized by disturbances of thrombopoiesis and megakaryocyte development. Cytogenetic findings were correlated with clinical and hematological data in altogether 18 patients with acute nonlymphocytic leukemia (ANLL) and with inv(3) (13 patients) or t(3;3) (five patients), six of whom were male and 12 who were female. Chromosomal changes in addition to the 3q anomalies were demonstrated in 14 out of 18 patients, predominantly numerical and structural aberrations of chromosome 7 (12 cases) and/or abnormalities of 5q (five cases). Complex karyotype abnormalities were observed in six of 13 patients with inv(3), but in only one of five patients with t(3;3). In ten out of our 18 patients a preceding myelodysplastic syndrome (MDS) and/or exposure to mutagenic/carcinogenic agents had been established. In eight patients the morphology of ANLL blasts was immature (FAB subtype M1); in three patients ANLL-M4, and in two patients each ANLL-M5, M6, and M7 was diagnosed; in one patient with antecedent MDS the leukemic blasts were not classifiable according to the FAB criteria. A disturbed megakaryocyte development, characterized by an excess of micromegakaryocytes was observed in 14 patients, seven of them showed normal or elevated platelet counts as an unusual feature in patients with ANLL. The clinical course and outcome was extremely poor: 15 of 18 patients died within 10 months after the diagnosis of ANLL. Because of their missing response to conventional chemotherapy, patients with inv(3) or t(3;3) have to be estimated as at high risk. The characterization of genes affected by inv(3) or t(3;3) could help to elucidate molecular changes leading to impaired proliferation and differentiation of hematopoietic cells, also of the megakaryocytic lineage. Based on molecular genetic findings new therapeutical approaches could be designed.