Following a majority vote in the House of Commons, England has become the first country to legalise a procedure that combines the genetic material of three people (that of the two parents and a third woman) in order to produce a child without a hereditary genetic defect that causes mitochondrial diseases. The change will also pass down to future generations, completely ridding that child’s bloodline of the disease.

The so-called “three-person baby” procedure involves fertilising two embryos using the male’s sperm and one egg from each woman. The prospective mother’s embryo will contain defective mitochondria, while the donor’s embryo will not. The mother’s embryo’s nucleus is removed and placed inside the other, healthy embryo, which has its own nucleus removed. This process preserves all of the mother’s original genetic traits, such as personality and appearance, but the diseased mitochondria are replaced by healthy ones, preventing a whole slew of diseases and problems ranging from a type of diabetes to blindness and organ failure. According to Dr Gillian Lockwood, a reproductive ethicist, the procedure would not affect “height, eye colour, intelligence [or] musicality”. Prof. Doug Turnbull, who devised the technique at Newcastle University, describes the process as involving only 0.1% of the genetic material of the donor female. The first baby to host this modification could be born as soon as 2016.

It is a major step forward for a medical idea that has been disputed and in many cases opposed, both for safety and ethical reasons. While the process that was legalised in the UK is different from what is typically termed “genetic modification”, it still raises questions about drawing ethical lines with regard to the modification of human beings.

Image: Johann van Tonder

In comparison, the leading technique for genetic modification in the sense of directly editing a living cell’s DNA is called Crispr, a technology inspired by bacteria defending themselves from viruses. When a virus is detected, the bacterium produces a type of enzyme that targets and cuts the invading virus’s DNA, disabling the virus. This technology has been used by scientists who use this DNA-cutting enzyme (called CAS9) to snip DNA in living cells and replace parts of it with synthetic genomes. Not only is Crispr superior to previous techniques in its simplicity and precision, but it can also be used to change many genes at once, an important attribute if the technique is to be used for the treatment of more complex diseases. The technique was invented by Dr Jennifer A. Doudna, a researcher at the University of California, Berkeley.

The discovery of the Crispr technique has led to a sudden and unexpected new era in genome editing. The technique could be used by scientists all over the world to genetically modify human embryos, among other types of cells, with previously unattainable accuracy. If the embryos are then used in conception, such genetic modifications would be hereditary and difficult to track and reverse. There is little global or national regulation concerning the technique, making it technically legal in many parts of the world. As a result, a large group of biologists, including Dr. Doudna, have published a paper in the journal Science calling for a worldwide moratorium on using Crispr technology clinically – or on humans who will be able to pass the genetic modifications on to other generations – until tests can be developed and the process optimised.

While the technique is highly efficient compared to previous techniques, it has yet to be streamlined and approved by authorities such as the Food and Drug Administration (FDA). Dr. David Baltimore, a former president of the California Institute of Technology and one of the scientists who called for the moratorium, believes human knowledge of genetics is simply too immature for such a powerful tool. To use it clinically would be to stumble around in the dark hoping for the best, says Dr. Baltimore.

While the moratorium is in effect, scientists around the world are morally bound to the wishes of the scientific community at large, but not legally. While this does not sound particularly reassuring, a similar moratorium was called in the 70s when genome editing first became possible, garnering interest among biologists all over the world. Dr. Baltimore was also a proponent of that moratorium, which he considered successful. He claims that “there is a moral authority you can assert from the US and that is what we hope to do.”

Until regulations on the gene editing tool can be established, it is likely that human experiments will be limited, and editing cells that can pass on hereditary characteristics will remain banned in over 40 countries.


Illustration: Faith Honey and Johann van Tonder

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