Fishing for ETV6/RUNX1 fusion and MLL gene rearrangements and their additional abnormalities in childhood acute lymphoblastic leukemia patients of Kashmir

Abstract

ObjectiveEvidence suggests that ETV6/RUNX1 translocation in pediatric acute lymphocytic leukemia shows geographical variation. Therefore, the present study aimed at unveiling the incidence of ETV6/RUNX1 fusion in pediatric acute lymphocytic leukemia cases of this region using fluorescent in-situ hybridization. Besides, we aimed to determine the incidence of MLL gene rearrangement and the pattern of chromosomal abnormalities in this study group. MethodsSamples from 57 acute lymphocytic leukemia cases of pediatric age group were subjected to fluorescent in-situ hybridization and conventional cytogenetic analysis using standard methods. ResultsConventional cytogenetic analysis revealed chromosomal abnormalities in 19.3% cases. The other major chromosomal abnormalities reported were monosomies in 10.5%, hypodiploidy in 7%, marker chromosomes in 3.5% and deletions in 3.5% cases. We found a 44,XX,-7,-18, r(5), i(17q) complex karyotype in one of the cases. Fluorescent in-situ hybridization analysis revealed ETV6/RUNX1 translocation to be present in 28.07% cases and MLL gene rearrangement in 3.5% cases. 12.5% of ETV6/RUNX1 fusion positive cases were found to have a loss of ETV6 allele. Besides, 8.8% cases were found to exhibit a signal pattern suggestive of RUNX1 amplification. ETV6 gene deletion and MLL gene amplification was detected in 3.5% cases each, of our study. ConclusionsFrequency of ETV6/RUNX1 fusion oncogene was found to be higher in pediatric ALL cases of Kashmir region as compared to that reported from other parts of India. Besides, a case was found to have a karyotype viz 44,XX,-7,-18, r(5), i(17q) that has not been reported elsewhere in the childhood ALL.