Miracle mitochondria or designer babies?

The United Kingdom’s genetics watchdog agency, the Human Fertilisation and Embryology Authority (HFEA), has granted permission to a team of Newcastle University scientists to create a human embryo that will have genetic material from two mothers.
The BBC reports that “The scientists will transfer the pro-nuclei – the components of a human embryo nucleus - made by one man and woman - into an unfertilized egg from another woman.”

The team and its supporters attribute the value of the research to the potential prevention of the maternal passing of certain genetic diseases to their unborn babies. The relevant genetic diseases, which are known as mitochondrial, arise from DNA found outside the nucleus and are inherited separately from DNA in the nucleus. Although the resulting egg would never be allowed to develop into a baby, if it did, the offspring would still resemble their mother and father because the mitochondrial DNA do not dictate things like hair color.
Mitochondria produce most of the energy that people need to grow and live. Organs such as the heart, brain, liver, kidney are particularly dependent on well functioning mitochondria. One unique feature of mitochondria is that they have their own DNA, which is inherited from the mother only. Faulty maternal DNA puts children at risk of developing a mitochondrial disease that can damage the cells of the brain, heart, liver, kidney and skeletal muscles and confine sufferers to a wheelchair. At present there is no known cure.
Some groups have expressed concern regarding the HFEA approval to proceed with the research. The potential scientific breakthroughs seem to evolve at a rate that surpasses accompanying decisions regarding ethics. Pro-life campaigners fear the decision to approve the research represents an unacceptable step towards the creation of "designer babies".
Professor John Burn, from the Department of Clinical Medical Sciences at Newcastle University, claimed such fears and criticisms to be unfounded. Professor Burn said that technically a baby could be born with two mothers - the DNA from the egg donor and the DNA from the mitochondrial donor. The ethical implications may resemble those regarding a surrogate mother donating an egg or carrying the intended parent's child that was conceived through IVF treatment - a process itself that once generated an abundance of controversy.
[thanks Ana Lita]