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  • Writer's pictureJohn Lantos

This is not a three-parent child



A strange paper recently appeared in Nature, reporting that some (“fewer than five”) babies had been born in the UK following a procedure known as mitochondrial replacement therapy (MRT.) The report was strange because it was not coming from the researchers who performed procedure. Instead, it was a story about a different story that appeared in The Guardian which had uncovered the information about the babies by submitting a freedom-of-information request to the Human Fertilization and Embryology Authority (HFEA) the government agency that oversees and regulates such procedures. HFEA had no further comment. The only comment from the researchers was that scientific papers have been submitted to journals and are undergoing peer-review.


As of now, we know nothing about the babies. We don’t know how many procedures were down, why they procedures were done, whether they were initially successful, or what outcome measures are being studied to determine whether to do more. The reason given for the secrecy was that it was to preserve privacy and confidentiality. But surely they could have published the protocol or reported general results without identifiers. That is done all the time.


A prior FOI request revealed that the first 17 attempts at MRT did not result in pregnancy.


The secrecy about results is in stark contrast to the openness of the process by which the regulations for conducting such research were developed. That process took more than a decade and was open to public scrutiny in a way that seemed to be a model for combining expert opinion with exercises in deliberative democracy. “The public dialogue work concluded that the public were generally supportive of these techniques, although concerns around safety, the donor role and the regulation of the techniques were highlighted.”

Through this process, the HFEA guideline limits the use of MRT to patients for whom pre-implantation genetic diagnosis may be inappropriate and probably unsuccessful. For such couples, MRT is the only option for producing a potentially healthy and genetically related child. These guidelines are based on the ethical argument that an unproven treatment such as MRT s should only be used when no proven treatment is available.


Each case must be approved by the HFEA. More information about approvable protocols can be found on the HFEA website.


Mitochondrial disease affect about 1/6000 live births. That means that about 650-700 babies are born with such diseases in the US every year. Many children with such diseases look normal at birth but then, over the first months of life, develop progressive weakness, neurocognitive disabilities, seizures, and respiratory failure. Most die in the first months of life. A successful therapy would allow parents to have healthy, biologically related children.

The UK has some of the world’s most permissive laws regarding this procedure. In many countries, including the United States, the procedure is completely banned (though at least one doctor from the US traveled to Mexico to perform such a procedure.) The process by which they are banned is, itself, mired in secrecy. The ban was added as a rider to an omnibus budget reconciliation act. Nobody knows who put it in. It has to be renewed every year.


Why such secrecy? Why is this potential beneficial treatment banned?


Much of the controversy about MRT stems from ambiguity about whether it should be considered a form of germ-line gene therapy (GLGT). It shouldn’t. It is quite different from other forms of germline gene therapy. Typically, in GLGT, the goal is to alter the nuclear DNA (rather than the mitochondrial DNA) of a potential parent, and so, for example, give birth to a child without the gene for, say, cystic fibrosis or sickle cell disease. This altered germ line DNA would then be passed on to future generations.

But that is not what is going on with MRT. No DNA is not altered. Instead, the child will have all of its nuclear DNA from its mother and father, and unaltered mitochondrial DNA from the donor of the (enucleated) ovum. The popular press – and some scientific journals – have described such children as having “three parents.” That is as nonsensical as imagining that the recipient of a transplant or a blood transfusion was now “two people.”


The controversy has led to the procedure being banned in many places and, where not banned, carefully regulated. That is good. But the secrecy surrounding MRT is not good. Either the procedure should be banned altogether as too risky to try in humans, or it should be done in a transparent way so that the world can know the results and come to informed judgments about the risks. If the babies born after the procedure are initially healthy, then we will be left with the same sorts of questions that surround many other innovative treatments, questions about rare side effects or unforeseen long-term health problems. Data that would allow answers to those questions will only come with careful long-term follow up studies.


Given that research on MRT is permitted in some countries, the research will continue. Given the controversial nature of the procedure, it will be surrounded by secrecy. We can do better. We owe it to the babies and the families suffering from mitochondrial diseases to do better. Let’s examine the evidence and then base policy on facts, not fears.




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