CRLF2 and acute lymphoblastic leukemia: For example, the Children’s Oncology Group (COG) uses tiered screening algorithms, employing TaqMan low-density array cards for NCI high-risk B-ALL, followed by sequential genomic profiling (e.g., evaluation of CRLF2 expression, FISH for CRLF2 rearrangement and Sanger sequencing for JAK1/JAK2 mutations for cases with high CRLF2 expression, and RT-PCR and/or transcriptome sequencing for cases with low CRLF2 expression) (12).