How mitochondrial donation involved in three parent babies works
TheTelegraph.co.uk – by The Agency, February 3, 2015
MPs will tomorrow decide whether mitochondrial donation allowing IVF babies to be born with DNA from three different people should be made legal.
The technique involves replacing DNA in an egg in order to prevent devastating inherited mitochondrial diseases.
What are mitochondria?
Mitochondria are tiny rod-like structures in cells which act as power houses, generating the energy that allows our bodies to function. Unusually, they have their own DNA, distinct from the genetic material within the cell nucleus. Mitochondrial DNA (mDNA) makes up about 0.1% of a cell’s total DNA and does not affect individual characteristics such as appearance and personality.
What causes mitochondria disease?
Harmful mutations in mitochondrial DNA can prevent the mitochondria working properly, resulting in a number of diseases some of which can be serious and life threatening. They may affect major organs and cause conditions ranging from poor vision to diabetes and muscle wasting.
How are mitochondria diseases passed on?
Children may inherit mitochondrial DNA defects from their mothers, but not their fathers. People with faulty mDNA can develop symptoms or be carriers of the condition without experiencing ill-effects themselves.
What is mitochondria donation?
Defective mDNA from a mother’s egg can be replaced with healthy mDNA from a donor. This will then prevent the harmful mutations being inherited and passed onto future generations.
What are the techniques involved?
There are two different procedures, one carried out before fertilisation and the other after.
Maternal Spindle Transfer (MST) involves first removing the nuclear DNA from a donor egg whose mitochondria are healthy. The “spindle” of chromosomes containing the mother’s nuclear DNA is then taken from her egg and inserted into the donor egg. As a result, the donor egg is left with nuclear DNA from the mother and mDNA from the donor. This healthy egg is then fertilised and implanted into the mother’s womb.
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