Mitochondria are organelles which provide the energy to cells. Mitochondrial DNA is inherited from the mother. There are a number of genetic mitochondrial disorders which can cause stroke, blindness, ataxia, neuropathy, and a disorder termed Leigh syndrome.

DNA blood tests can diagnose these disorders as well as identifying mothers who are “carriers.” It is estimated that 2500 women of childbearing age in the UK carry this risk.

A team led by Professor Doug Turnbull in the UK has developed the “pro-nuclear transfer” technique. Nuclear material of the parents’ fertilized egg, which contains the damaged mitochondria, is removed and is implanted into a donor’s healthy egg from which the nuclear material has been removed. The undamaged mitochondria of the donor’s egg remains. There is a similar technique in the US, but there, fertilization takes place after the parents’ DNA is implanted into a healthy egg.

Which mother does the child look like? Mitochondrial DNA contains only 37 genes compared with 23,000 in the nuclear genome. Thus, the donor will have little effect on the child’s DNA.

As expected there are religious objections. Nevertheless, the UK will likely approve this procedure to start in 2016.

The above is a summary of an article by Andrew Jack in the Financial Times, January 20, 2016.

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