ABSTRACT
Lymphocytes of 37 Iranian patients with B-cell chronic lymphocytic leukemia were stimulated with different mitogens i.e., phorbol myristate acetate [PMA], pokweed mitogen and Staphylococcus aureus Cowan I. Adequate metaphases were obtained in 23 subjects following PMA stimulation. Cytogenetic analysis of G-banded mitosis showed both numerical and structural abnormalities. The most frequent abnormality observed in this study involved chromosome 21 [-21 in four cases and +21 in three cases]. Trisomy 12 and 15 as well as structural abnormalities and other alterations related to chromosomes 2, 3, 6, 7, 10, 12, 18 and 19 were also observed. The high frequency of numerical abnormalities involving chromosome 21 found in this study may be considered as a characteristic feature of B-CLL in Iran