A rare inherited defect in calcium channels that predisposes to cardiac arrhythmia and sudden death has been cited as a plausible explanation for the deaths of children of  Kathleen Folbigg, who is  currently serving a 30-year prison sentence for infanticide.

Ms Folbigg was convicted in 2003 of smothering four of her children over a ten year period, but scientists now say her conviction should be overturned because it was made prior to the discovery of a genetic mutation called “CALM2 G114R” that predisposes to ventricular fibrillation, catecholaminergic polymorphic ventricular tachycardia, or mild long QT syndrome.

Calmodulinopathies are rare life-threatening arrhythmia syndromes caused by pathogenic variants in one of the three genes (CALM1, CALM2, and CALM3) that encode identical calmodulin proteins

A rare calmodulinopathy mutation was present in two children and thus a fatal arrhythmic event may have been triggered by their intercurrent infections, they argue in a paper published in EP Eurospace.

Professor Carola Vinuesa and Dr Todor Arsov, from the Australian National University (ANU), first found the novel variant in the gene “CALM2”, by genome sequencing Ms Folbigg in 2018.

The “G114R” variant in the CALM2 gene, which is predicted to cause lethal cardiac arrhythmias, was found in both Ms Folbigg and her two daughters.

In their paper, they state that “biochemical and electrophysiological studies of the G114R variant show that it has deleterious effects on calcium binding and regulation of the two pivotal calcium channels involved in cardiac excitation contraction coupling, CaV1.2 and RyR2, in a similar manner to that of the pathogenic G114W and N98S variants.”

They therefore consider the variant likely precipitated the natural deaths of the two female children.

In addition, the two male children carried biallelic rare missense variants in BSN, a gene shown to cause early onset lethal epilepsy.

The paper is authored by international researchers in cardiac inherited disorders including, Professor Peter Schwartz of the Centre for Cardiac Arrhythmias of Genetic Origin, Milan

They emphasise that their findings apply to cases beyond that of Kathleen Folbigg.

“The growing understanding of inherited cardiac arrhythmias forces a reassessment of the medical foundations, never challenged, on which several mothers were found guilty of infanticide on the basis of assumption instead of evidence,” they wrote.

“The genomic revolution heralds a new era for the assessment of recurring familial sudden deaths of infants and children, an era based on a presumption of innocence for tragically unlucky families, until proved otherwise,” the paper concluded

Professor Vinuesa added: “This discovery could help mothers across the globe. Whole genome sequencing has the potential to explain sudden infant deaths.”

However the research findings came too late to be included in a 2019 inquiry into Ms Folbigg’s convictions, which concluded that there was no natural cause for the Folbigg children’s death.

This omission has led to a petition for Ms Folbigg’s conviction to be reviewed, signed by 90 prominent scientists including Australian Academy of Science President, Professor John Shine, public health researcher Professor Fiona Stanley and former Chief Scientist Professor Ian Chubb .

They noted that Ms Folbigg had been convicted bases on ambiguous diary entries rather than solid evidence or facts.

“It is deeply concerning that medical and scientific evidence has been ignored in preference of circumstantial evidence. We now have an alternative explanation for the death of the Folbigg children,” said Professor Fiona Stanley.