It was revealed that the common missense variant NUDT15:NM_018283.2:c.415C>T (Arg139Cys, dbSNP: rs116855232 T allele) conferred susceptibility to thiopurine-induced leukopenia in a genetic dose-dependent manner, with an odds ratio (OR) of 35.6 [16]. Here, NUDT15 is linked to Decreased total leukocyte count.