As the number of leukopenia events is strongly associated with TPMT and NUDT15 variants (Relling et al., 2011; Cargnin et al., 2018; Soler et al., 2018), we also subdivided the sample according to the presence or absence of TPMT and/or NUDT15 variants. The gene discussed is NUDT15; the disease is Decreased total leukocyte count.