Three-parent baby

Three-parent babies are potential human offspring that will have three genetic parents.^[1][2][3] The procedure is intended to prevent mitochondrial diseases including muscular dystrophy and some heart and liver conditions.^[4] It is the subject of considerable controversy in the field of bioethics. Scientists have already produced pregnancies in which the fetuses contain DNA from three parents, but none have yet been brought to term.^[5]

The process is currently prohibited in the United States, but is being actively researched in China.^[5][6] Some research is also taking place in the United States and in the United Kingdom.^[4]

Technique

The process of producing a three-parent baby involves taking the nucleus of one egg and inserting it into the cytoplasm of another egg which has had its nucleus removed, but still contains mitochondrial DNA, and then fertilizing the hybrid egg with a sperm. The purpose of the procedure is to remove a nucleus from a cell with defective mitochondria and place it in a donor cell with healthy mitochondria, which after fertilization will contain a nucleus with genetic material from only the two parents.^[5]

Although the donor egg is said to contribute only 0.1% to the genetic make up of the child, when examining the genetic material of these children there are still 3 identifiable genetic parents.^[7] This is due to the fact that the donor egg came from a non-maternal relative. For the child to have only 2 identifiable genetic parents and still have underwent this procedure, the donor egg must have come from a maternal relative because maternal mtDNA is almost identical. Maternal relative egg donation is not commonly used, however, because if the female egg has a mitochondrial disease then it is highly likely that the maternal relatives inherited the disease as well.

Ethics

New York University researcher James Grifo, a critic of the American ban, has argued that society "would never have made the advances in treating infertility that we have if these bans had been imposed 10 years" earlier.^[5]

Opponents argue that scientists are "playing God" and that children with three genetic parents may suffer both psychological and physical damage.^[8] These critics include Alison Cook of Great Britain's Human Fertilization and Embryology Authority, who argues that bans were "written to protect the welfare of the embryo and the child."^[5]

The mito-mom(female with healthy mitochondria) and the geno-mom(female with the genomic nucleus) go through vigorous test and are involved in potential risks for physical and psychological threats associated with the requisite medical procedures.^[9] Both patients incur the physical and psychological risks of hormonal stimulation and egg retrieval, but only one of them gets the benefit of having a child. The in-vitro fertilization(IVF) patient has the potential benefit of having a child. The female that provides the egg; her potential benefit is a more emotional and possibly financial result. An ethical dilemma left contested is, do these potential benefits for both patients compensate for the potential harm?^[9]

Most procedures present are classified as cloning. Other procedures are still in the preclinical trials, being performed on animals with some extent to humans.^[10] The most common procedure that is done on humans and is FDA approved is done by meiotic spindle-chromosomal complex transfer followed by fertilization, preimplantation embryo development and embryonic stem cell derivation.^[10][11] Of this transferring of mitochondria to the oocytes, trials have showed 53% showing abnormal fertilization, giving it only less than 50% chance that the fertilization will be viable.^[11] Given all the vigorous test and risks, it is not always certain it will work and therefore majority of this vacillating process will have to be re-done.^[9]

The children produced from this type of procedure are also a main concern. This procedure is meant to avoid the potential risks associated with mutated mtDNA including blindness, neurodegenerative disease, diabetes, muscular dystrophy and death.^[7] Considering only the benefits associated from removing mutated mtDNA, this procedure seems ethical. However, this type of procedure is still relatively new and not much information about long-term health effects are known. Could the child still inherit mutated mtDNA from the maternal nuclei?^[12] How will future generations be effected? There is currently no way of telling what future consequences will occur in the genetic child or its progeny until this method is further studied with humans.^[9]

The concern with three-parent babies, is it applies to genetic modification to avoid illnesses, as well as genetic modification for the improvement of the human race.^[9] An important investment of resources is into research of avoiding inherited diseases being passed down generation to generation. Though this type of scientific investment is keen on scientific excellence, it is also to be in account of its social significance.^[9] The sociological approach assumes that biology alone is not able to successfully enable human reproduction. That it is in needed of these procedures involving IVF, especially three-parent embryos, for the increasing survival of the human kind.^[13]

Some other issues can be solved from implementing this procedure. Cryopreserved embryos will not only be used for IVF reproduction but for mitochondria transferring as well.^[14] A survey was done by Fertility and Sterility in 2008 that 40% of patients that have frozen their embryos are undecided on what is to be done with them once they have already conceived a child.^[15] While other problems, like adoption, will more likely take a suffering toll.^[9]

External links

• Three-parent IVF needs more research, review says - BBC News article
• Short film with experts discussing the ethical / practical issues surrounding 'Three Parent Babies' / 'Mitochondria Replacement'

References