Major complications in the therapy by HCT include “minimal residual disease/leukemia” (MRD/L) that can lead to leukemia relapse, graft-vs.-host disease (GvHD) in cases of immunogenetic MHC/HLA or minor histocompatibility antigen mismatch (Singh and McGuirk, 2016) and opportunistic infections (Sahin et al., 2016; Schuster et al., 2017). This evidence concerns the gene HLA-C and leukemia.