In an exhibit tendered to a Sydney inquiry examining Folbigg's convictions, world-leading genetics researcher Peter Schwartz says the CALM2 variant identified in her make-up and in that of two of her four dead children is enough to re-examine their deaths.

"My conclusion is that the accusation of infanticide might have been premature and not correct," Professor Schwartz wrote.

Folbigg was jailed for at least 25 years in 2003 after she was found guilty of killing her four babies - Caleb, Patrick, Sarah and Laura - in the decade from 1989.

The four children all died aged between 19 days and 19 months.

The CALM2 variant is a gene associated with long QT syndrome - a heart rhythm condition which can potentially cause fast, chaotic heartbeats increasing the risk of palpitations, fainting and sudden death.

Professor Schwartz, recognised worldwide as a leading expert in long QT syndrome, said the identification of the variant in Folbigg and her two female children raises "significant doubts to a significant extent".

Two other experts, Professor Edwin Kirk and Dr Michael Buckley, argue the variant may have contributed to but wasn't the sole cause of death for Laura and Sarah.

"It is possible the variant is pathogenic but is unrelated to the cause of death of Sarah and Laura," they said in an exhibit to the inquiry.

"For this to be the sole cause of death for Sarah and Laura, an exceptional clinical scenario would be required."

The NSW government in August 2018 agreed to a judicial review of Folbigg's convictions with hearings held in March and May this year.

Former NSW District Court chief judge Reginald Blanch QC, who presided over the inquiry, can refer the matter to the Court of Criminal Appeal if he finds there is reasonable doubt as to Folbigg's guilt.

Australian Associated Press