Résumé
Our understand of the pattern of chromosomal changes with the affected cells of patients with various hematological disorders has expanded enormously in the past years. Therefore, the work was carried out at Pediatric and Histology Departments in Zagazig University Hospital to evaluate the particular patterns of chromosomal changes in some blood diseases of children. Sixty patients with some blood diseases, aged 5-15 years old of both sexes and 15 children as control were included. All patients were subjected to full clinical and laboratory investigations in addition to full family history. Blood samples were collected from all cases for chromosomal study preparation. Phytohaemoagglutinin were added to all culture tubes to stimulate cell division. After 72 hours mitosis was stopped at metaphase stage by adding colchicine, the metaphase spreads were stained by Geimsa technique. Karyotyping was performed to all examined cases. The metaphase spreads of the patients with leukemia revealed abnormal chromosomal pattern in 73.3% of 15 patients. The main numerical aberrations were polyploidy, while the main structural aberrations were duplications or deletion of one arm of chromosomes 4, 5 and 15. Increased breaks and translocation were noted in many leukaemic cases. While the patients suffering from idiopathic thrombocytopenic purpura showed abnormal chromosomal pattern of 46.7% of the cases. The main detected aberrations were duplication of the long arm of chromosome 5 and deletion of long arm of chromosome 8. 30% of 15 cases of aplastic anemia showed chromosomal abnormalities. The recorded aberrations were duplication of long arm of chromosome 6 and short arm of X chromosome. Lastly, the main recorded chromosomal aberrations in cases of favism were satellite formation of acrocentric chromosomes of group D and G in two cases out of 15 cases with glucose 6 phosphate dehydrogenase deficiceny. In conclusion, chromosomal abnormalities are common in childhood leukemia than in aplastic anemia and idiopathic thrombocytopenia