Abnormalities of chromosome 1 in myeloproliferative disorders.

Three patients with myeloproliferative disorders showed a similar chromosome abnormality, accompanied by other abnormalities that were different in each case. Marrow cells from all three patients were trisomic either for the entire chromosome 1 or for its long arm. Patient 1 had a brief period of anemia and thrombocytopenia which preceded a terminal acute leukemia; Patient 2 had polycythemia vera (P.V.) that terminated in acute leukemia; and Patient 3 has P.V. The detection of an abnormal karyotype in Patients 1 and 2 was an important factor in establishing the diagnosis of acute leukemia. Preliminary evidence supports the suggestion that some chromosomal changes are nonrandom in myeloproliferative diseases. Nonrandom abnormalities involving the same chromosome have been observed in several human neoplastic disorders.