A mother, a former registered nurse and Sydney Islamic sect leader convicted in Australia's first female genital mutilation court case — seen as a breakthrough in prosecuting the crime — have been acquitted by an appeal court.

Key points: It was Australia's first female genital mutilation prosecution

It was Australia's first female genital mutilation prosecution The trio had their convictions quashed after new expert evidence came to light

The trio had their convictions quashed after new expert evidence came to light The evidence revealed the two sisters genitals remained intact

In November 2015, a jury found the mother, who cannot be named for legal reasons, and former nurse Kubra Magennis guilty of cutting the genitals of two sisters aged around six and seven during ceremonies at homes in Wollongong and Sydney's north-west.

WARNING: This story contains graphic details that may be confronting to some readers

Shabbir Vaziri, a head cleric and spiritual leader in the Dawoodi Bohra community, was found guilty of being an accessory for directing members to lie about the practice of 'khatna', a procedure involving the nicking or cutting a girl's clitoris in the presence of female elders.

The mother and Ms Magennis were sentenced to 11 months' home detention, while Mr Vaziri received a maximum 15-month full-time custodial sentence and was later granted bail pending an appeal.

But the New South Wales Court of Criminal Appeal has quashed the convictions of all three after reviewing new expert evidence, namely that the tip of the clitoris was still visible in each girl.

"While having regard to the whole of the evidence, and the summing up, it cannot be concluded that the jury would have come to the same decision had the new evidence been available at the trial," the judgement read.

"Therefore a potential miscarriage of justice has been established."

The appeal court's decision came despite evidence from a Westmead Children's Hospital Child Protection Unit specialist, Dr Susan Marks, that there might be no long-term evidence of cutting or nicking in the form of visible scarring due to excellent blood supply to that area of the body.

Dr Marks' evidence at trial was that she could not see the tip of the clitoris in each girl, leaving it to the jury to decide whether the pair had had them removed.

Shabbir Mohammedbhai Vaziri had been handed a maximum 15-month sentence. ( AAP: Dan Himbrechts )

"One possible explanation that was before the jury at trial as to the inability of Dr Marks clearly to visualise the tip of the clitoral head … that would have supported a finding of guilt in respect of the appellants, is no longer available," the judgement said.

The appeal heard expert evidence that a possible explanation for being unable to previously visualise the glans was the girls being prepubescent prior to trial.

It was the defence case at trial that 'symbolic khatna' had been performed with no cutting involved, described by Magennis as a ceremony whereby "skin sniffed the steel".

The appellants also argued a cut or nick did not amount to mutilation.

The appeal court determined not to order a retrial on alternative allegations of assault occasioning actual bodily harm.