The 5q- deletion: Correlation of breakpoints with the immunophenotype of leukemic blast cells

Cytogenetic and immunologic features of 13 patients with the 5q- deletion with the diagnosis of acute leukemia, either as the blastic transformation of a typical 5q- syndrome or myeloproliferative disorder or as a de novo presentation, were studied. Variable 5q- breakpoints were identified: the common interstitial deletion at q13q33 was found in nine cases, and a terminal deletion at q13, q22, q22, q31, respectively, was found in four cases, two of which had unbalanced translocations. A comparison of 5q- breakpoints with the blast cell immunophenotype indicated an association of myeloid and TdT⁺/myeloid leukemias with interstitial deletions and of monoblastic phenotypes with terminal deletions.