SATIS The 'Three parent baby'

SATIS The ‘Three parent baby’.

This topic was chosen following an item in the news, reported in the Guardian December 15th 2016; ‘First UK baby with DNA from three people could be born next year’. ‘The UK’s fertility regulator gave the green light for clinics to seek licences for this procedure’. ‘The Human Fertilisation and Embryology Authority (HFEA) announced that it would accept applications from clinics wanting to offer this controversial therapy after it met to consider the latest scientific evidence for the safety of the procedure’. ‘The regulator’s decision was described as a “momentous and historic step” by Adam Balen, chairman of the British Fertility Society, and ‘comes nearly two years after Parliament voted to legalise the procedure’. ‘Doctors in Newcastle are ready to offer the experimental treatment, called ‘Mitochondrial Replacement Therapy’ (MRT) to women whose faulty DNA puts them at risk of passing on devastating genetic diseases to their children. They intend to apply for a licence immediately and could begin treating patients as early as Spring 2017’.

(the process was licenced in the USA two years ago)

Read the full article at; https://www.theguardian.com/science/2016/dec/15/three-parent-embryos-regulator-gives-green-light-to-uk-clinics

Some basic cell biology.

With a few exceptions, all human cells contain cytoplasm within a cell membrane. Inside the cytoplasm there is a nucleus, but also many other much smaller ‘organelles’, including mitochondria. Mitochondria are responsible for generating energy from glucose and oxygen, and as such are more numerous in cells which need a lot of energy.

The nucleus of each cell contains 23 pairs of chromosomes, one of each pair originating from the male parent the other from the female. The chromosomes are made up of a large number of genes, and the genes are composed of a complex chemical called Deoxyribose Nucleic Acid (DNA). It is these genes which are responsible for inherited characteristics.

However, the mitochondria also contain some DNA, though not organised onto Chromosome-like structures.

Faults, or ‘mutations’ of this mitochondrial DNA can be responsible for cells which do not produce energy correctly and this gives rise to a number of inherited ‘mitochondrial diseases’ which occur in about 1 in 10,000 babies. These diseases cause brain, heart, muscle and other energy-demanding tissues to fail resulting in a long debilitating disease and early death.

The Mitochondrial Replacement Therapy works by removing the nucleus from the egg of a mother who is carrying the mutated mitochondrial DNA and injecting into an egg from a healthy donor. This egg is then fertilised in-vitreo by sperm from the mother’s partner and replaced into the mother at a very early stage of development.

Thus the only DNA from the donor is the mitochondrial DNA which is not concerned with inherited features.

An article in Nature outlined some concerns with this process. Primarily there seems to be some chance of removing some ‘diseased’ mitochondria along with the Mother’s nucleus, with the risk of the disease re-appearing in the developing child.

Read full article at;  http://www.nature.com/news/uk-moves-closer-to-allowing-three-parent-babies-1.21067

Discussion;

  • Is the phrase ‘three parent baby’ a misleading media ‘hype’?

  • Are the mitochondria with mutated DNA produced as a result of damaged / mutated DNA in the nucleus, in which case the procedure will not work?

  • If a child is born as a result of this procedure, but then develops an inherited  mitochondrial disease, will there be a case for litigation?

  • Where does funding for this process come from and is it justified?

The group then watched a TEDx video in a different but related area.

This lecture, by Jennifer Kahn focussed initially on a project which resulted in mosquitoes which were unable to carry the malarial parasite;---potentially a major development in the fight against this highly significant disease. The problem then would be how to breed and release enough mosquitoes with this genetic trait to make a difference to the spread of the disease.

A genetic tool known as CRISPR has been produced which effectively by-passes normal ‘Mendelian’ genetics and results in extremely rapid transfer of a new genetic trait to a whole population. This has been demonstrated in fruit flies and in some fish including Asiatic Carp. It seems to be a very simple procedure that could be ‘carried out by a reasonably intelligent High School student’. The implication is that it could be used to create significant alterations in whole species.

Link to this 10 minute video;

https://www.ted.com/talks/jennifer_kahn_gene_editing_can_now_change_an_entire_species_forever

Discussion;

  • Is there evidence as yet that this process would work in ‘higher animals’ including humans?

  • Could this be used as a weapon? Eg. Producing a wasp with a much more dangerous sting which could then spread across a whole species?

  • If use of this tool could be used to eliminate Malaria; --- should it be? And in any case, what control could be exerted over its use?

  • Producing and rapidly disseminating a genetic trait which resulted in infertility could result in a species becoming extinct within a very short space of time. What would be the cost/benefits of using this? Japanese Knotweed? Encroaching  species of crayfish? Grey squirrels?

  • Could CRISPR be used as a therapeutic tool to ‘correct’ genetic mutations in an adult?