In October 2015 controversial techniques to create three and four-parent babies became legal.
This was after new regulations allowing research into Maternal Spindle Transfer (MST) and Pro-Nuclear Transfer (PNT) were backed by the House of Lords by 280 votes to 48 in February the same year. The House of Commons had already voted 382 to 128 in favour of the regulations.
Research into both techniques involves the destruction of embryos, and though the stated aim of the procedures is to create children free from mitochondrial disease, they will not help women and children who already have the conditions.
MST involves replacing the nucleus in a healthy donor egg with the nuclear DNA from the prospective mother – resulting in a child with DNA from three parents.
PNT creates a child from four different individuals (a chromosomal mother, a chromosomal father, an egg mother and a sperm father).