Last week, the British House of Commons passed a Bill legalising mitochondrial DNA transfers — three-parent in vitro fertilisation (IVF) — triggering a spate of debates on the ethics of using the technique, which some say would lead to the making of “designer babies”.
Commonly called “three-parent babies”, the children conceived through the technique will carry DNA from three parents.
However, the supporters of the technique say that it would be a blessing for couples who have been longing for a baby for years but are unable to conceive due to maternal mitochondrial defects. They argue that these children will have about 99.99 percent of their DNA from their two parents and “an infinitesimal fraction” — about 0.01 percent — from the third person, the woman whose egg provides the healthy mitochondria.
Mitochondria is the powerhouse of the cells in our body and any defect in it may lead to serious disorders such as heart and liver disease, respiratory problems, blindness and muscular dystrophy.
Studies say that in Britain, around 2,500 women suffer from mitochondrial disorder or faulty mitochondria, which results in recurrent miscarriages. Mitochondrial DNA is inherited from the maternal side. So any defect in maternal mitochondria will be inherited by the offspring. Around the world, there are thousands of babies who are born with diseases due to mitochondrial mutations.
Mitochondria are tiny organelles inside a living cell, floating apart from the nucleus in the cytoplasm, creating energy for the cell’s activities. Though most cells’ DNA is in the nucleus, each mitochondrion has its own set of 37 genes, inherited exclusively from mothers.
Like the rest of the DNA, mitochondrial DNA can be subject to mutations. For reasons not yet clear to scientists, these mutations do not affect the mother who passes them on but they can affect the offspring, often killing them. Mitochondrial diseases are devastating and incurable. Studies show that between nine and 12 of every 100,000 people have a mitochondrial disease. Parents who have a child who is sick with a disease(s) due to mitochondrial mutations are caught in a dilemma as they know that the next child can also be sick because of the mitochondrial defect.
Scientists in the US and UK have been working to develop a procedure to replace a mother’s defective mitochondrial DNA through an IVF technique called mitochondrial replacement therapy (MRT).
The MRT technique uses DNA from three persons to produce an embryo, removing the faulty maternal mitochondria. For this, a donor egg whose nucleus containing the genetic material is removed and the maternal nucleus is inserted into the egg. This hybrid egg is fertilised with the paternal nucleus to produce the embryo. The resulting embryo thus will contain nuclear material from the three “parents”.
The procedure is done using two methods. The first is done before the fertilisation of the egg. This is known as “maternal spindle transfer”, in which the nucleus of the unhealthy egg containing defective mitochondria is removed and is implanted into a donor egg with healthy mitochondria (the nucleus of the donor egg is removed before implantation). The second procedure is done after fertilisation, and is known as “pronuclear transfer”. The nucleus from the unhealthy egg is removed and implanted into a healthy donor egg with healthy mitochondria. This is then transferred back to the biological mother for further gestation.
Earlier, the technique was called cytoplasmic transfer.The first healthy baby girl born after successful cytoplasmic transfer was Emma in 1997 at the Institute for Reproductive Medicine and Science of Saint Barnabas Medical Center in Livingston, New Jersey, US. She was born after her mother, Maureen Ott, 39, had to undergo infertility treatment for more than six years before cytoplasmic transfer was done using a donor’s cytoplasm.
In 2000, Alana Saarinen was born in the US using the same technique. Her parents had to go through four unsuccessful attempts of IVF treatment before the fifth cytoplasmic transfer became successful. However, after Alana was born, the Food and Drug Administration banned the technique citing safety and ethical issues.
It is mostly anti-abortion activists and the Catholic Church who lead the opposition to the method, saying that any alteration of human eggs is altering humans.
Bishop John Sherridon told The Catholic Herald: “Whilst the Church recognises the suffering that mitochondrial diseases bring and hopes that alternative methods of treatment can be found, it remains opposed on principle to these procedures where the destruction of human embryos is part of the process. The human embryo is a new human life with potential; it should be respected and protected from the moment of conception and not used as disposable material.”
While appearing on Today programme on BBC Radio 4, Britain’s Conservative MP Jacob Rees Mogg said: “At the moment, there is a very clear boundary that babies cannot be genetically altered and once you have decided that they can, even for a small number of genes, you have done something very profound and then it’s merely a matter of degree as to what you do next.”
Biotechnology and ethics experts in India are a tad sceptical about the technique. With IVF clinics mushrooming across the country, the debate cannot be too far away from India.
Dr Prachin Ghodajkar, assistant professor at the social medicine department, Jawaharlal Nehru University, feels that the society should first understand the difference between sociological parents and biological parents.
“The question of biological parents comes into frame only at the time of a dispute between the couples,” he said. “Otherwise, no child will want to clarify his or her parents. Due to these new medical interventions, the process of adoption by childless couples will come to a standstill. In India, before legalising or taking any decision about the new law, people from different social backgrounds should discuss and debate the topic.”
Dr Geeta Goswami, scientific director, Ridge IVF Centre, New Delhi, believes that the majority, but not all, of the inherited mitochondrial disorders are due to nuclear genes encoding proteins targeted to mitochondria.
“So, by just changing the mitochondria will not solve the problem,” she said. “There can be newer interactions between nuclear and newly introduced mitochondrial genes in the treated embryo/ fetus. The outcomes are unknown. Without knowing the definitive outcome, such decisions seem premature and overshadow important genetic, social and ethical concerns. “Such experiments should be first carried out in animal systems where fully developed embryos and offspring can be studied over several generations and any changes, genetic or epigenetic occurring due to new mitochondria and nucleus can easily be studied.”
However, Dr Robert Klitzman, professor of psychiatry at Columbia University and director of its Masters of Bioethics Program, begs to differ. “I appreciate their (critics’) concern, but an unfertilised human egg is by no means a full human being,” he said. “It is not even an embryo. And thousands of lives can be saved if this therapy is successful.”
In a Wall Street Journal article, Dr Klitzman, whose latest book is The Ethics Police? The Struggle to Make Human Research Safe argues, “While news media portray MRT as producing children with three parents, the analogy and the way the controversy is framed are misleading. A more accurate analogy would be to organ transplantation. If I receive a kidney from a donor, no one says that I then consist of two people. One kidney, weighing perhaps 1 pound (450 gm), now rests in my 185-pound (83 kg) body and allows me to live. Similarly, to replace less than one out of every 100,000 bits of DNA in an individual with DNA from someone else makes no major difference to the recipient’s identity other than to allow him or her to survive.”
While it is true that man cannot be god or is most unlikely to crack the code of life, all we can do is use scientific technology to better living conditions without stepping into unethical practices.