Reproductive cloning, which created Dolly the sheep in 1997, involves transferring the nucleusof an adult cell into an egg, giving the resulting embryo a full setof genes without the normal sperm-meets-egg fertilisation step.
His group is especially interested in promoting the technique for treating mitochondrial diseases -- these organelles posses a different setof DNA than that contained in the nucleusof cells, and are responsible for generating the energy needed for cells to function.