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mitochondriafigure1England’s Chief medical Officer, Sally Davies has recommended that the UK government introduces regulations to enable couples at high risk of having mitochondrial disease to be allowed to have IVF and use mitochondria from a healthy donor. This involves a change in the germ line [inheritable DNA] and ‘We would be the first country to allow this practice.’ she said.

tough mitochondria

Mitochondria, as all of those studying biology know are the ‘batteries’ of the cell providing the majority of energy from respiration. When mitochondria become faulty there are a range of problems from muscle weakness, heart disease and early dementia. About 1 in 200 babies born will have mitochondrial disorders. Doctors have tried to rectify these by injecting donor mitochondria into faulty cells but this has not been successful as they are so small and easily damaged.

tired mitochondria

Mitochondria are probably the remnants of a symbiotic relationship with bacteria. They were probably bacteria that were engulfed by cells; these cells then had a massive evolutionary advantage being able to generate 15 times as much ATP [the energy currency of a cell]. Mitochondria are the same size as bacteria, also contain circular DNA, have bacterial type ribosomes and enzymes and have a double membrane like bacteria.

mitochondrial disease 2

Mitochondria are outside the nucleus and are not involved in fertilisation of the sperm and egg nuclei.  Mitochondria are solely inherited from the mother – the egg cell mitochondria present in the cytoplasm will form the foetal mitochondria.  Doctors have recently developed techniques to prevent mothers passing on mitochondrial diseases to their children. In this new technique the nucleus from a fertilised egg cell will be placed into a donor egg cell with normal mitochondria that has had its nucleus removed. The nucleus will contain genetic information from the parents – mother and father and the enucleated egg cell [egg cell without a nucleus] from a third person. The newly formed embryo will thus have genetic information from the original two parents and genetic mitochondrial information from the donor –‘three parents.’ This will cause a genetic change which will be passed down the line to other generations.3 parent baby

This affects what the HFEA describes as the germ line. Tampering with germ line is illegal and to many conjures up the spectre of eugenics and slippery slopes which lead to ‘designer babies‘. It requires a change in the law to make it legal. HFEA [the Human Fertilisation and Embryology Authority] have involved the public in consultation  which has has been generally in favour of a change in the law and now the Chief Medical Officer has publicly expressed her views. It’s all over to the Law Lords now to decide when the issue is debated later this year!  

mitochondrial disorder