Cytogenetic studies on patients with chronic T cell leukemia/lymphoma

Cytogenetic studies were performed on 3 patients with chronic T cell leukemia and on 1 patient with T cell lymphoma. One of the patients had leukemic cells derived from a suppressor T cell clone, another expressed OKT3, 4, and 8, and cells of the other 2 were derived from a helper T cell clone. All patients had an abnormal karyotype in peripheral blood or bone marrow cultured with or without mitogen. Modal chromosome numbers were 42 and 44/45 in 1 patient each and 47 in the other 2. The structural and numerical abnormalities involved almost all chromosomes, except no. 19 and the X chromosome. All patients had a rearrangement of the long arm of no. 14, with a break at band 14q11; 3 patients also had a break at 14q32. An inversion of 14q occurred in 2 patients; a tandem translocation involving both no. 14 chromosomes and a translocation between no. 14 and no. 17 each occurred in 1 patient. The break in 14q at band q11 in our cases resembles the chromosome change reported in ataxia telangiectasia. This provides added support for the proposal that a 14q rearrangement involving band q11-12, with or without an accompanying break in 14q32, may confer a proliferative advantage on lymphocytes, especially on those of T cell origin.