Donor treatments for mitochondrial DNA disorders are ethical

13 June 2012

The Nuffield Council on Bioethics has published its findings on the ethics of using donor techniques to prevent mitochondrial disorders.

The report of the six month long consultation concludes that such techniques are ethical, provided that they are shown to be effective and safe, and that families undergoing treatment are given adequate information and support.

Mitochondrial disorders are inherited maternally, from a small number of genes located outside the nucleus of the mother’s egg on mitochondrial DNA. Mutations in these genes can result in a number of serious disorders being passed from mother to offspring.

Techniques intended to prevent transmission have been developed whereby a donor egg has its nuclear genetic material replaced with that of the affected mother. The resulting child will still inherit half of its nuclear genes from each parent, but would receive the healthy mitochondrial DNA of the donor.

Such methods have been demonstrated in laboratory tests, but are not currently permitted for treatment in the UK. The Human Fertilisation and Embryology Act 2008 prohibits the implantation of an embryo whose DNA - nuclear or mitochondrial - has been altered.

The most controversial aspects of these treatments are that the genetic contribution from the donor suggests that offspring effectively have ‘three parents’, and that it is a germline therapy that will be passed down the female line to all future generations.

The Council found that the aspects of egg donation that imply parenthood and identity do not apply to mitochondrial donation, and so such donors should not be accorded the same status as reproductive egg donors; i.e. they should not be regarded as a biological parent nor be legally required to be identifiable to offspring. They conclude that the germline changes are acceptable in the particular instance of preventing mitochondrial DNA disorders, and that it is ethical to proceed with further development of these techniques in order that they can be considered for use as treatments. The full report can be accessed on the Nuffield Council on Bioethics website.