DNA discovery key to overturning conviction of child killer Kathleen Folbigg

World-leading experts on the rare gene mutation believed to have led to the deaths of convicted child killer Kathleen Folbigg’s daughters have made a ‘significant discovery’.

Kathleen Folbigg in 2019. Picture: AAP

World-leading experts on the rare gene mutation believed to have led to the deaths of convicted child killer Kathleen Folbigg’s daughters, have made a “significant discovery” that could further scientific understanding of how the variant affects the body’s function.

An inquiry into Folbigg’s conviction over the deaths of her four children has been told that Danish genetics experts Michael Toft Overgaard and Mette Nyegaard have made a “new finding” that after they carried out further tests.

Folbigg was convicted in 2003 of smothering her children Caleb, Patrick, Sarah and Laura, but genetic evidence that she and her daughters carried a rare mutation linked to heart irregularities has raised the possibility they died from natural causes.

Geneticists believe Sarah and Laura’s death may have been the result of a mutation in the CALM2 or calmodulin gene, of which Folbigg is also a carrier.

Professor Overgaard, who along with his wife and research collaborator Professor Nyegaard, is a leading expert on calmodulin, told the inquiry they had made a new link between calcium levels, calmodulin and a type of membrane protein, called sodium channels which needed further research.

“There is a new finding that a particular mutation will give a particular strong effect on the binding of the sodium channel,” Professor Overgaard said.

“We hope not too many people are listening because in science we are in a competition with one another and the first one to try and publish gets all the glory. By doing this we invite all the competitors to run for the race, but for us this is more important.”

Professor Nyegaard confirmed the CALM2-G114 ­mutation in the Folbigg DNA was likely to have led to the deaths of Sarah and Laura.

“From where we stand and what we can see … it looks like a bad variant,” she said.

The inquiry heard that prior to 2012 the scientific community had not believed it was possible to have a mutation in the calmodulin gene, because it was so “essential to life” and was consistent in living organisms ­including yeast, worms and mice as well as humans.

However, Professor Nyegaard said the data on the variant had been skewered by its ­extreme “incompatibility” with life, comparing the mutations to planes during World War II which were so badly hit in a critical spot that they were not able to return to base.

“The worst hit planes are not coming back,” she said.

Though the CALM2 mutation was only detected in Folbigg and her daughters, her sons Caleb and Patrick were found to have mutations in the BSN gene, which has been associated with seizures.

The inquiry, chaired by former NSW Supreme Court chief justice Tom Bathurst, was scheduled to continue this week but the hearings have been pushed back to February in light of the new findings.

The success of Folbigg’s bid for freedom will depend on the strength of the genetic evidence, which has been backed by more than 150 experts who signed a petition pushing for her release. The inquiry will also examine psychological evidence including incriminating diary entries.