H2AX and gastrointestinal stromal tumor: Regarding the MPLA-measured cohort, the CHEK2-deleted primary GISTs showed significantly older ages at presentation than those harboring intact CHEK2 (p = 0.033, 66.03 ± 11.81 vs. 58.1 ± 9.28 years), but they showed no association with the clinicopathologic factors or expression statuses of γ-H2AX and 53BPl by either staining method, indicating their very early role in GIST inception.