PDCD1 and acute lymphoblastic leukemia: Previous research on the relationship between SNPs and HSCT outcomes [29] found that the C-allele of rs36084323 in the promoter region of the PDCD1 gene in donors was associated with a higher risk of CMV (p = 0.0265) and relapse (p = 0.0356) in ALL patients, while the G-allele of rs5839828 (p = 0.0265) increased the risk of relapse in ALL patients.