Clinical and Experimental Study in 21 Cases of Acute Leukemia with Trisomy 4.

To explore the clinical and experimental features of acute leukemia(AL) with trisomy 4, a retrospective study on the clinical and laboratory data in 21 cases of AL with trisomy 4 was performed. Chromosomes were prepared using direct method and/or short-term(24h) cultures of bone marrow cells. Karyotypic analysis was carried out using R- banding techique. 14 cases were studied by interphase FISH using a chromosome 4-specific α-satellite DNA probe labeled by spectrum Green to ascertain the presence of a clone with trisomy 4. 5 cases with t(8;21) revealed by karyotypic analysis were detected by dual-color FISH using t(8;21) translocaton probe to confirm the AML1/ETO rearrangement. The patients with AL and trisomy 4 had a median age of 50 years and a median survival of 10 months. They all had de novo AL expect two cases with secondary AL. M2 was the most frequent FAB subtype in this series (9/21 cases). The initial leukocyte count more than 10×10⁹/L was seen in 16 cases. An enlargement of liver, spleen and/or lymph nodes in varying degrees was found in 15 cases. Among 15 cases received immunophenotypic analysis, 11 cases showed CD34 positivity and 6 cases co-expressed myeloid and lymphocytic antigens. Karyotypic analysis disclosed clonal trisomy 4 in 18 cases and one cell with +4 in 3 cases. Isolated trisomy 4 was found in 7 cases, while 14 cases had other abnormalities besides trisomy 4 including numerical abnormality (+6) in one case, and structural abnormalities in 13 cases among which t(8;21) was found in 8 cases. Interphase FISH confirmed that all 13 cases including 3 cases having one cell with +4 on karyotypic analysis had clonal trisomy 4. Dual-color FISH confirmed that all 5 cases with t(8;21) had AML1/ETO rearrangment. So we concluded that AL patients with trisomy 4 had unique clinical features and a poor prognosis.