Cytogenetic Profile of Acute Lymphoblastic Leukaemia in South India: A Series of 1,819 Patients from a Single Centre

INTRODUCTION: Cytogenetic findings are critical for determining prognosis, therapy and risk assessment in acute lymphoblastic leukaemia (ALL). Data on the epidemiology of cytogenetic findings in ALL from southern Asia is limited. This report documents the cytogenetic changes in ALL seen at a referral hospital in southern India and compares it with the literature. METHODS: Clinical profiling and conventional cytogenetic analysis (CCA) of all patients with reverse-transcription polymerase chain reaction for detection of cryptic t(12;21). RESULTS: Of 1,968 ALL, 1,819 (92.4%) patients aged 0.3-84 years (median 17) had successful CCA. There were 979 children (≤18 years) and 840 adults. Abnormal karyotypes were found in 1,368 (75.2%), B-ALL-78%, and T-ALL-69%. The favourable-risk group included high hyperdiploidy (HeH, 17.4%), t(12;21) (9.8%), and t(1;19) (4.3%), with >80% of HeH and t(12;21) in children. The unfavourable-risk group included t(9;22) (11.2%, 80% adults), hypodiploidy (8.0%), MYC (8q24) translocations (2.3%), and KMT2A (11q23) translocations (1.6%). In children, the frequency of HeH (26.8%) was lower than the West (30.7%) but higher than South-East (S.E.) Asia (15.5%) while t(9;22) (4.2%) was higher than the West (2%) but lower than S.E. Asia (6.8%). In adults, frequencies again differed from S.E. Asia (HeH, 6.4% vs. 2.7% and t(9;22), 19.4% vs. 29.3%) but were comparable to the West. CONCLUSION: CCA effectively provides diagnostic information in over 90% of ALL cases. While the spectrum of cytogenetic changes is similar to global data, there are significant regional variations in the frequencies of specific abnormalities.