Recent studies used CRISPR-C, which is a technology that uses Clustered Regularly Interspaced Short Palindromic Repeats to generate extrachromosomal circular DNA (30), to generate ecDNA containing the dihydrofolate reductase (DHFR) gene in the HAP1 cell line of chronic myelogenous leukemia in humans. This evidence concerns the gene DHFR and chronic myelogenous leukemia, BCR-ABL1 positive.