CALR and chronic myelogenous leukemia, BCR-ABL1 positive: In the group of Ph-negative MPN preceding CML (9/24 cases), data on the CALR type were available in 8/9 cases, of which CALR type 1 was detected in 4/8 (Klairmont et al., 2018; Xia et al., 2019; Liu et al., 2020) and CALR type 2 (5-bp insertion) in 4/8 cases (Bonzheim et al., 2015; Boddu et al., 2018; De Roeck et al., 2018; Sobieralski et al., 2022).