Scientists search gene alterations in three-parent kids

By Dr. Ananya Mandal, MDFeb 6 2012

Researchers from Australia want to find out if using the DNA of three parents will prevent children inheriting life-threatening diseases. They add that if the technique proves successful in preventing the transfer of mitochondrial DNA mutations from mothers to babies, then laws on the use of embryos will need to be changed to allow the procedure.

The researchers explain that around one child a week is born in Australia with such mutations that can affect the way the body converts food into energy, damaging muscle and nerve function and causing organ failure, strokes, and growth and hearing problems. The proposed technique to prevent this involves transferring a mother's chromosomes into a donor egg that has had its chromosomes removed but has healthy mitochondrial DNA present. Then, as in normal IVF treatment, the eggs would be fertilized with sperm and the resultant embryo could develop. A second technique would first allow the father's sperm to fertilize the egg and then transfer the mother's and father's chromosomes to a healthy donor egg.

Professor Justin St John, of the Centre for Reproduction and Development at the Monash Institute of Medical Research in Victoria, says it is unclear whether researchers can legally test proposed techniques to eliminate a mother's faulty mitochondrial genes. “We certainly couldn't go out and make new embryos.” But Prof St John says it might be possible to test the procedure using eggs that have been arrested in development. “We think we could use discarded material but that needs to be clarified - whether we can do that and whether the law needs to be changed for that to happen,” he told AAP.

The federal government is reviewing the laws relating to the use of embryos in research. Prof St John said a few more years of testing and research were needed to determine the safety and effectiveness of the technique. “We have to make sure we don't do the baby any harm we haven't previously foreseen.” Prof St John said it was imperative for investigation of the technique to proceed and for the Australian law to embrace the technology if it proved successful. “To introduce that into clinical practice and to make new embryos there would need to be a change in the law. I think the Catholic Church would be against it and certain pro-life groups would find that inappropriate,” Prof St John said.

“This would mean we are using the genes of three parents,” IVF Australia's Professor Peter Illingworth said. Prof Illingworth defended the procedure, saying it was “not properly understood” and “would not affect the child's genetic make-up”. Genes that determined behaviour and appearance came from the nucleus of the cell - not the mitochondrion powerhouse of the cell, he said. The mitochondrial illness affects the way a body converts food into energy and can cause strokes, seizures, growth problems, hearing problems and organ failure.

“We want to remove the mother's bad mitochondria and replace them with healthy mitochondria through IVF,” Prof Illingworth said. “We know women who have defective mitochondria pass that on to their children.” Prof Illingworth said scientists were hopeful the Government would alter the law to allow further research. “The health implications of these sorts of diseases are so serious this research should be allowed,” he said. Professor David Thorburn, of the Murdoch Children's Research Institute in Melbourne, said he supported changing the laws in Australia.

Advocacy group NSW Right to Life and religious organisations including the Catholic Church opposed changes to the law in their submissions. “The human embryo is a discreet human entity,” NSW Right to Life wrote. “It is no less human than any other human person. Embryos are complete humans at the earliest stages of their human development. The creation and destruction of human embryos for experimentation is unethical and an offence against humanity,” it said.

The government is considering the submissions and says it will pass down its recommendations in the coming weeks.