Kathleen Folbigg spent twenty years in prison, accused of murdering her four children. But she was recently granted a full pardon and released from prison. A rare mutation in the CALM gene, which affects one in 35 million people, is known to have caused the deaths of her two daughters due to a rare syndrome called calmodulinopathy.
CALM is the gene that encodes the protein calmodulin, which is needed to control the movement of calcium around cells. Humans need all three CALM genes in order for the body to produce enough of this protein to control the rhythmic contractions of the heart. A mutation in one of the CALM genes can lead to an irregular heartbeat and cardiac death.
In 2012, scientists found that a mutation in one amino acid in the CALM1 gene caused irregular heartbeat and cardiac death in a large Swedish family. Studies in 2013 and 2016 showed that other types of mutations in the CALM1 and CALM2 genes can cause cardiac arrest in children.
A 2019 study found that in a group of 74 children with a mutation in the CALM gene, 27 percent died of a heart attack at the average age of 6. These data were presented by genetics experts during the Folbigg investigation.
In 2003, a jury concluded that Folbigg strangled each of her children to death for ten years. She was found guilty of three counts of murder and one count of manslaughter. She became known as “Australia’s worst female serial killer.
Folbigg always insisted on her innocence. There were no signs of strangulation or trauma to the children. The court focused on circumstantial evidence, namely Folbigg’s diary, in which she wrote that “guilt about them all haunts me.
At the time, the human genome had just been sequenced for the first time, at a cost of $300 million, so it was impossible to examine the children’s DNA for mutations that could explain their sudden deaths. But by 2015, the cost of sequencing the human genome had dropped to $1,500, and some studies of CALM gene mutations had been done that could help explain what happened to the Folbigg children.
Only 135 people worldwide are known to have a mutation in the CALM gene. Therefore, the Folbigg family would probably be the only case in Australia. Another mutation could have been the cause of her two sons’ deaths.
This case raises questions about how often gene mutations can lead to false murder charges. It is possible that other similar cases have been mishandled and gene mutations have not been taken into account in the investigation.
