CRLF2 and acute lymphoblastic leukemia: Deletions in the PAR1 region have been detected in various types of ALL and results in the fusion of the noncoding region of exon 1 of P2RY8 to the CRLF2 gene, which causes CRLF2 expression to be driven by the P2RY8 promoter [49–51] (Figure 4).