PAX5 and acute lymphoblastic leukemia: PAX5-ZCCHC7 structural variations are also observed in a subset of B-lymphoblastic leukemia (B-ALL), a neoplasm that demonstrates robust ZCCHC7 expression overall (Extended Data Fig. 7d), and especially in treatment-refractory cases, with PAX5-ZCCHC7 positive cases showing the highest levels of ZCCHC7 mRNA expression (Extended Data Fig. 7e).