First pre-birth genetic modification could be approved soon in the UK to correct faulty mitochondria

Forbes reports that at some point between now and July, 2014, the UK parliament is likely to vote on whether a new form of in vitro fertilization (IVF)—involving DNA from three parents—becomes legally available to couples. If it passes, the law would be the first to allow pre-birth human-DNA modification, and another door to the future will open.

The procedure involves replacing mitochondrial DNA (mtDNA) to avoid destructive cell mutations. Mitochondria are the power plants of human cells that convert energy from food into what our cells need to function, and they carry their own DNA apart from the nuclear DNA in our chromosomes where most of our genetic information is stored. Only the mother passes on mtDNA to the child, and it occasionally contains mutations that can lead to serious problems.

In Vitro Fertilization

Oxbridge Biotech describes the details of the procedure.

Dr Mitalipov, who headed the research, explained: “Using this process, we have shown that mutated DNA from the mitochondria can be replaced with healthy copies in human cells.” Indeed, by using 106 human eggs donated by healthy volunteers, the team demonstrated that although the ST-IVF grants chances of successful in vitro fertilization lower than the standard IVF (50% versus 75%), the viable embryos undergo normal development. More importantly, the rate of success is not impaired by use of cryo-preserved human eggs, a condition that will be critical for clinical applications of ST.

One mitochondrial replacement technology, is named maternal Spindle Transfer (ST).
An approach that could overcome the ban on destruction of human embryos is the emerging Nuclear Genome Transfer (NGT), which involves genetic transfer between two unfertilized eggs and has recently been proven safe.
Pronuclear Transfer (PT) is another reproductive technique. In PT, the maternal egg with faulty mitochondria is first fertilized in vitro. The resulting pro-nucleus, containing the maternal and paternal nuclear DNA, is then transferred into a donor egg with healthy mitochondria.

Mitochondria

Regardless of the particular technique used, a child born from any of ST, PT or NGT would genetically be the offspring of three parents, carrying the nuclear DNA of the mother and the father and the mitochondrial DNA of the donor mother, a prospect that has raised ethical concerns worldwide. Moreover, making changes to mitochondrial DNA could create a precedent to treat other serious and untreatable genetic conditions.

According to the journal Nature, an estimated 1 in 5,000-10,000 people carry mtDNA with mutations leading to blindness, diabetes, dementia, epilepsy and several other impairments (the equivalent of 1,000 – 4,000 children born each year in the U.S.). Some of the mutations lead to fatal diseases, like Leigh Syndrome, a rare neurological disorder that emerges in infancy and progressively destroys the ability to think and move.

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