FIGURE 2.

Mitochondrial donation techniques. Mitochondrial donation involves removing the nuclear genome from an oocyte (or zygote) that contains mutant mtDNA and transferring it to a donor oocyte (or zygote) with wild-type mtDNA that has its own nuclear genome removed. The reconstituted oocyte (or zygote) contains the nuclear DNA from the intending parents and the mtDNA from a donor. Mitochondrial donation can be performed between unfertilised human oocytes using a technique called (a) maternal spindle transfer (MST) or between fertilised human zygotes using a technique called (b) pronuclear transfer (PNT).