t(12:21) is underrepresented in childhood B-lineage acute lymphoblastic leukemia in Punjab, Pakistan

Molecular genetic studies on 167 pediatric ALL patients from different areas of Pakistan confirm a low frequency of the favorable prognosis fusion oncogene TEL-AML1 (t 12; 21) in underdeveloped countries of the region

TEL-AML1 fusion oncogene (t 12; 21) is the most common chromosomal abnormality in childhood acute lymphoblastic leukemia (ALL). This translocation is associated with a good prognosis and rarely shows chemotherapeutic resistance to 3-drug based remission induction phase of treatment as well as overall treatment. Thus, the higher the frequency of this fusion oncogene, the easier to manage childhood ALL in a given region with less intensive chemotherapy. Although global frequency of TEL-AML1 has been reported to be 20-30%, a very low frequency has been found in some geographical regions, including one study from Lahore, Punjab, Pakistan and others from India. The objective of present study was to investigate if this low frequency of TEL- AML1 in pediatric ALL is only in Lahore region or similar situation exists at other representative oncology centers of Pakistan. A total of 167 pediatric ALL patients were recruited from major pediatric oncology centers situated in Lahore, Faisalabad, Peshawar and Islamabad. Patients were tested for TEL-AML1 using nested reverse transcription polymerase chain reaction (RT-PCR). Only 17 out of 167 (10.2%) patients were found to be TEL-AML1 positive. TEL-AML1+ALL patients had favorable prognosis, most of them (82.4%, 14/17) showing early remission and good overall survival. Thus, our findings indicate an overall low frequency of TEL-AML1 in Pakistan pediatric ALL patients, in accordance with lower representation of this prognostically important genetic abnormality in other less developed countries, specifically in south Asia, thus associating it with poor living standards in these ethnic groups. It also indicates ethnic and geographical differences in the distribution of this prognostically important genetic abnormality among childhood ALL patients, which may have a significant bearing on ALL management strategies in different parts of the world.