Acute Lymphoblastic Leukemia Sequencing

The ETV6-RUNX1 fusion gene, found in 25% of childhood acute lymphoblastic leukemia (ALL), is acquired in utero but requires additional somatic mutations for overt leukemia. We used exome and low-coverage whole-genome sequencing to characterize the critical secondary events associated with leukemic transformation. RAG-mediated deletions emerge as the dominant mutational process, accounting for at least 43% of genomic rearrangements and characterized by the presence of recombination signal sequence motifs near the breakpoints; incorporation of non-templated sequence at the junction and a ten-fold enrichment at promoters and enhancers of genes actively transcribed in early B-lineage development. Single-cell tracking shows that this mechanism i... (Read more)

The ETV6-RUNX1 fusion gene, found in 25% of childhood acute lymphoblastic leukemia (ALL), is acquired in utero but requires additional somatic mutations for overt leukemia. We used exome and low-coverage whole-genome sequencing to characterize the critical secondary events associated with leukemic transformation. RAG-mediated deletions emerge as the dominant mutational process, accounting for at least 43% of genomic rearrangements and characterized by the presence of recombination signal sequence motifs near the breakpoints; incorporation of non-templated sequence at the junction and a ten-fold enrichment at promoters and enhancers of genes actively transcribed in early B-lineage development. Single-cell tracking shows that this mechanism i... (Read more)

Changes in gene dosage are a major driver of cancer1, engineered from a finite, but increasingly well annotated, repertoire of mutational mechanisms2-6. These processes operate over levels ranging from individual exons to whole chromosomes, often generating correlated copy number alterations across hundreds of linked genes. An example of the latter is the 2% of childhood acute lymphoblastic leukemia (ALL) characterized by recurrent intrachromosomal amplification of megabase regions of chromosome 21 (iAMP21)7,8 To dissect the interplay between mutational processes and selection on this scale, we used genomic, cytogenetic and transcriptional analysis, coupled with novel bioinformatic approaches, to reconstruct the evolution of iAMP21 ALL. We... (Read more)