Mitochondrial Donation

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MITOCHONDRIAL DONATION

 

Mitochondrial donation is an IVF technique (also known as mitochondrial replacement IVF technique, mitochondrial transplant or mitochondrial replacement) that could prevent transmission of mitochondrial disease (mito) from mother to child.

Currently this technique is not available in Australia.  AMDF is beginning to engage with MPs, Senators and government officials to change government legislation to allow families affected by specific types of mito the chance to have disease-free children.   The process will involve the CEO, board members, scientists, patients and their families meeting with politicians to support the change. To be successful, we need the help of the mito community. Find out how you can help.

What is Mitochondrial Donation?

The two new mitochondrial donation techniques being developed are maternal spindle transfer and pronuclear transfer. They involve transferring nuclear genetic material from the affected mother’s egg into a donor egg that has had its nuclear DNA removed and retains only its healthy mitochondrial DNA; the resulting child therefore does not inherit the mitochondrial disease.

 

Mito cell for websiteThree People’s DNA?

Children who have undergone mitochondrial donation will have DNA from three people. However, it is important to note that when the new mitochondrial DNA molecule is introduced, it is only replacing 37 mtDNA genes (contributing about 0.1 per cent of a person’s genetic make-up), compared with approximately 22,000 genes in the nucleus, which are not replaced. The mtDNA contribution is important for converting food into energy but appears to make no significant contribution to appearance, behaviour or other features, which are determined by the nuclear genes and environment.

 

Some groups have made sensationalist claims about the techniques being inappropriate because the children could be said to have three parents. However, this is “misleading, inappropriate and unhelpful” according to the Nuffield Council on Bioethics in London, which in 2012 reviewed the procedures from an ethical standpoint.

Mitochondrial replacement can be compared to changing the sparkplugs in an engine or a transplant into a patient with organ failure.

What happened in the UK?

After an extensive process involving many years of consultation and three separate expert reviews, regulations to allow mitochondrial donation have been approved by the UK Parliament:

  • On Tuesday 3 February 2015 MPs in the House of Commons voted by 382 to 128 to allow mitochondrial donation.
  • On Tuesday 24 February 2015 peers in the House of Lords voted by 280 to 48 to allow mitochondrial donation to be licenced for use.

The UK Human Fertilisation and Embryology Authority (HFEA) is now charged with issuing a licence for these techniques to be used therapeutically on a case by case basis. To view the draft legislation, click here.

US developments towards mitochondrial donation

Following a study by an expert committee, on 3 February 2016 the Institute of Medicine of the US National Academies of Sciences, Engineering and Medicine recommended that initial clinical investigations of mitochondrial replacement techniques (MRT) should be considered by the US Food and Drug Administration under certain conditions.

These conditions include limiting access to women who are at risk of transmitting a severe mitochondrial genetic disease that could lead to a child’s early death or substantial impairment; and, for the time being, only allowing male embryos created through mitochondrial replacement to be implanted for pregnancy, to preclude any unforeseen consequences being passed to future generations.

The Mitochondrial Replacement Techniques: Ethical, Social, and Policy Considerations Report in Brief is available here.

The National Academies of Sciences, Engineering, and Medicine media release is available here.

Australian Legislation governing mitochondrial donation

Research and clinical applications of mitochondrial donation are overseen by laws made by federal and state governments. State laws are, for the most part, consistent with federal law.

In all states, legislation prohibits the use of mitochondrial replacement techniques in the clinic, and research is significantly restricted.

In all states except Western Australia, research on a limited range of mitochondrial donation is permissible up to day 14 of embryo development, subject to a license being granted. In 2010, the Hon. Mark Butler MP, then Federal Minister for Mental Health and Ageing, appointed an independent committee to review the two relevant acts: the Prohibition of Human Cloning for Reproduction Act 2002 and the Research Involving Human Embryos Act 2002. The committee’s report, released on 7 July 2011, recommended the existing legislation remain unchanged. To view the report, click here.

How many Australians could benefit from mitochondrial donation?

A recent publication in the New England Journal of Medicine – Mitochondrial Donation: How Many Women Could Benefit – estimates that “the average number of births per year among women at risk for transmitting mtDNA disease is 152 in the United Kingdom and 778 in the United States”.

A simple extrapolation from UK would be approximately 56 births per year in Australia given the respective population sizes and assuming roughly equal age distribution and fertility.

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