The Possible Association between Constitutive Heterochromatin Polymorphism and Human Leukemias

Objective: Polymorphism of the size of heterochromatin region of chromosomes has been well documented in human genome and it consists of DNA sequences that are not transcribed. The prime aim of the present study was to evaluate the heterochromatin polymorphism associated with chromosomes in leukemic patients. Materials and Methods: The study was conducted on 35 consecutive leukemic patients and 34 healthy individuals in Modaress and Taleghani hospitals, Tehran, Iran between 2004-2006. By applying Barium Hydroxide saline Giemsa (BSC) method with certain alterations, the variant heterochromatin polymorphism of chromosomes 1, 9 and 16 on bone marrow and peripheral blood lymphocyte cultures were evaluated. Chi-square and Fisher s exact tests were used for statistical analysis with SPSS software. Results: Constitutive heterochromatin polymorphism of chromosomes 1 and 9 in leukemic patients revealed statistical significant differences when compared with chromosomes of healthy controls (p=0.0005) and (p=0.006) respectively. The differences were not significant for chromosome 16, it was 11.4% in leukemic patients and 0% in the control group (p=0.05). The frequency of partial and complete inversions did not show any significant differences between the leukemic patients and the control group. Conclusion: The constitutive heterochromatin polymorphism blocks may provide an opportunity to serve as a marker for the detection and characterization of the chromosomes in leukemic patients.