Nonhuman mammal whose mtDNA is from a nonhuman mammal resistant to a selected disease or disorder and whose nDNA is from a nonhuman donor mammal more susceptible to the selected disease or disorder

A nonhuman mammalian zygote or a nonhuman mammalian embryo whose cell or cells comprise mitochondrial DNA (mtDNA) from a first nonhuman donor mammal resistant to a selected disease or disorder and comprise nuclear DNA (nDNA) entirely from a second nonhuman donor mammal more susceptible to the selected disease or disorder compared to the first nonhuman mammal, wherein the donor resistant to the selected disease or disorder and the donor susceptible to the selected disease or disorder exhibit distinct mtDNA haplotypes.