Prevalence and patterns of high hyperdiploidy in Pakistani Paediatric B-lymphoblastic leukaemia

Objective: To determine the prevalence and cytogenetic patterns of high hyperdiploidy in Pakistani children with B-lymphoblastic leukaemia. Method: The retrospective, descriptive, cross-sectional study was conducted at the Cytogenetics Laboratory, Indus Hospital and Health Network, Karachi, and comprised data from November 2020 to August 2022 of paediatric patients aged 1-16 years of either gender who had been diagnosed with B-lymphoblastic leukaemia. Standard G-banding techniques were used and karyotypes were evaluated using a semi-automated system. Data was analysed using SPSS 25. Results: Of the 562 paediatric patients included in the study, 342 (60.9%) were males and 220 (39.1%) were females, with an age range of 1-16 years. Cytogenetic aberrations were identified in 289 (51.4%) cases, while 273 (48.6%) had normal karyotypes. Overall, 171(30.4%) cases displayed high hyperploidy. Gains were seen in chromosomes X, 4, 6, 10, 14, 17, 18 and 21. In all instances, chromosome 21 displayed increased activity by a 100% frequency gain. High hyperdiploidy (chromosome 51-65) was revealed to be the most common subtype of hyperploidy. Translocation t(1;19) was the most common structural aberration observed in association with hyperdiploidy. Conclusion: High hyperdiploidy was the most prevalent chromosomal abnormality found in paediatric B-lymphoblastic leukaemia patients. Consistent trisomy of chromosome 21 and frequent structural aberrations were also noted.