Likewise, preceding studies reported a high frequency of MPO immunoreactivity in adult ALL of B- but not of T-cell lineage (17-23%) involving the majority of blasts in positive cases (Arber et al., 2001; Du et al., 2020), and negative or lower FCM results as well (Ahuja et al., 2018; Du et al., 2020). The gene discussed is MPO; the disease is acute lymphoblastic leukemia.