Partial trisomy of the long arm of chromosome 1 in myelofibrosis and polycythemia vera.

We have identified partial trisomy 1q in 2 patients with different hematologic disorders. The first patient was a 55-year-old female with myelosclerosis and myeloid metaplasia diagnosed at age 38 years presenting with anemia, fatigue, bruising, fever, and splenomegaly. At age 56, she had 50--95% myeloblast cells and 95--100 nucleated RBC precursors per 100 WBC. Chromosome analysis of unstimulated leukocytes with Q, G, and C banding showed 46,XX,-6,+t(1;6) (q25;p22) in all metaphase cells. In vitro incorporation of Fe55 was demonstrated 90% of metaphases by autoradiography. The second patient, a 49-year-old male, was diagnosed as having polycythemia vera at age 30 during a regular checkup. He since developed hepatosplenomegaly. Chromosome analysis from a direct bone marrow preparation at age 44 and 45 showed grossly normal karyotypes. At age 49, his marrow by Q and G banding showed almost 100% of cells with 46,XY,-13,+t(1;13) (q12;p12). Eleven cases of trisomy of 1q have been reported in various hematologic disorders. It is apparent that partial trisomy 1q represents another nonrandom chromosomal abnormality, in addition to the most common nonrandom chromosomal aberrations, such as the Philadelphia chromosome, trisomy 8, trisomy 9, and monosomy 7 in hematologic disorders.