Wan et al. [18] reported that Cu-toxicity-induced downregulation of COPT5 was greater in higher Cu-tolerant HF/Mp than in less Cu-tolerant HF/Mb [‘Hanfu’ (Malus domestica) scions grafted on M. prunifolia (Mp) and M. baccata (Mb), respectively] leaves, and that the expression level of COPT1 was lower in leaves of HF/Mp than in leaves of HF/Mb when exposed to Cu-toxicity. The gene discussed is SLC31A1; the disease is hydrops fetalis.