Though this headline admittedly somewhat embellishes the story, it is not pure fiction; a baby has been born in the UK with DNA from three different people. In fact, there could even be more ‘three-parent’ babies as, for confidentiality reasons, the UK’s Human Fertilisation and Embryology Authority (HFEA) only states the figure as “less than five”.
In a cutting-edge new IVF procedure called Mitochondrial Donation Treatment (MDT), tissue from the egg of a healthy female donor is used in a bold attempt to protect the child from harmful hereditary diseases, mostly without a cure. The use of third-party tissue leaves a trace of third-party DNA in the baby’s genetics - about 37 genes out of 20,000.
Though the word ‘parent’ might be a strong one for an anonymous donor who imparts less than 0.2% of the child’s DNA, the appellation ‘three-parent babies’ seems to have caught on in the media surrounding it. But this sensationalist reporting, of which this article’s headline is equally guilty, must not detract from the fact that MDT is a significant milestone in natal medical care and the fight against genetic disorders.
Who Is MDT For?
The treatment is used to prevent those with mutated mitochondria from passing on genetic conditions to their offspring. When a woman has mutated and unhealthy mitochondria, this has a strong chance, close to certain, of being inherited by the child. This leads to mitochondrial disease.
Rare, vicious, and incurable, the impaired mitochondria, traditionally the powerhouse of the cell, fail to generate enough energy to keep the cells running either by being too inefficient or not working altogether.
And with this energy imbalance comes a plethora of symptoms. As mitochondria are found in over 90% of human cells, this disease affects many areas of our biology and causes many symptoms, including but not limited to developmental delays, fatigue, liver failure, diabetes, seizures, paralysed muscles around the eyes, nausea, inability to swallow, irregular heartbeat, pain or muscle cramping, blindness, deafness, and death. Looking at an article by MedicineNet, it is hard to find an aspect of the human body that is not marred by this disease. Therefore, this treatment is critical to minimising the onset of this disease.
How Does It Work?
Essentially, MDT works by removing the nucleus from the mother’s egg while discarding the unhealthy mitochondria, ultimately saving the gene-carrying core of the egg. The same process is carried out on a donor’s oocyte with healthy mitochondria, but this nucleus is not kept. Then, the mother’s nucleus is implanted into the donor egg.
There are two techniques for executing MDT, though the fundamentals outlined above are the same. The difference is that one occurs before the egg has been fertilised and the male’s sperm fertilises the new egg. The other after fertilisation has occurred, with a fertilised nucleus being transferred.
What Are The Risks?
As with all medical procedures, especially those involving pregnancy, it comes with some substantial risks. Firstly, there are of course all the risks of regular IVF. Miscarriages, birth defects, and stress in particular but also the intense financial pressures that can come with such an expensive procedure.
But on top of this, with MDT there is the added risk of it not working or the donor egg rejecting the nucleus. In an effect called “reversion”, a slight amount of damaged mitochondria that are carried across with the nucleus multiply at a rate greater than expected, causing mitochondrial diseases to occur and rendering the whole process entirely pointless. This typically occurs around weeks 12-13 of pregnancy, but not exclusively.
What Does The Future Look Like?
These are not the first “three-parent” babies to be born. In 2016, an operation was performed in Mexico on a Jordanian woman who, after multiple miscarriages and two children who died young, successfully gave birth to a healthy, disease-free baby.
But progress in this area has been slow, and the procedure has been controversial. Britain was the first country to legalise MDT in 2015; hence, the first baby/ies have been born here since the first operation seven years ago. The Newcastle Clinic became the only national clinic licensed to perform it shortly after and began to approve cases in 2018. COVID-19 clearly caused setbacks in MDT, but recent successes spark hope for a future of the treatment.
Unfortunately, it is still illegal in most other countries. It is a criminal offence in both the US and Canada, where it is seen as a form of genetic modification, despite only 0.18% of genes being transferred. Particularly in the US, where religious concerns hold more weight in politics, medical procedures garner far more debate and discussion around ethical issues that often bar them from progress.
Australia recently - October 2022 - legalised MDT in ‘Maeve’s Law’ and appears to be following in the UK’s footsteps, awarding $15 million to one licensed clinic to perform a clinical trial with ongoing monitoring.
While evidently still cemented in the research stage, hopefully, the UK’s recent successes will see an advancement of MDT. It is possible that we are a step closer to making mitochondrial diseases the anachronism that they could be.