After nearly four years of tests, frustration and confusion, in July her daughter Brianna was diagnosed with autism spectrum disorder.

More than 200,000 Australians have autism but it is diagnosed four times more in males than in females and experts now believe the skewed gender ratios reflect the failings of diagnostic processes rather than natural incidence rates.

Danuta Bulhak-Paterson is a clinical psychologist who specialises in autism spectrum disorder (ASD).

She said diagnostic criteria were developed specifically around presentation in men, so disseminating new research which showed how autism manifested differently in girls was key to fixing this glaring gap in care.

"Autism is much tougher to spot in the girls," she said. "Girls have very different presentation to boys on the spectrum. They are often better at camouflaging their difficulties. Due to the way female brains are wired they are better at reading emotion in others and imitating others in order to fit in."

A new study by advocacy group Yellow LadyBugs has revealed 51 per cent of girls on the spectrum had no access to early intervention support and 48 per cent endured repeated and costly assessments before receiving a diagnosis.

The advocacy group now connects more than 600 young women and their families whose stories highlight how starkly different the experience of ASD is for females.

At home with her mum Brianna talked excitedly about making "friends who will be just like me" at the first Canberra Yellow Ladybugs event to be held on November 27.

The happy "almost eight" year old is a world away from the emotionally drained little girl that would come home from school, fall in a heap and cry, her mother said.

"She was doing a lot of what they call masking where she would try to put on a brave face with everyone around her at school and then come home and release all her anxiety at home."

Doctors believed Brianna suffered from anxiety but her parents felt there was something more to it.

They noticed her sensitivity to noise on occasion and saw her struggle to cope with unexpected changes to routine.

A concrete diagnosis of high functioning autism came as a relief but also gave the family a foothold – a chance to vie for NDIS funding support and better understand Brianna's needs.

"Her school, Holy Spirit in Nicholls,has been amazing with our family," she said. "Since the diagnosis they have accommodated all her needs and it's so important to us that everyone involved with her is on the same page."

Yellow Ladybugs has made a submission to the United Nations Office of the High Commissioner for Human Rights.

Ms Koullas said there was a discrepancy between men's and women's access to care and exposure to harm due to misdiagnosis which needed to be addressed.

"I'm hoping that the Australian government can see exactly what we are dealing with. The survey exposes some really unfortunate truths about what females are going through. They need to invest in programs that better support and address this issue.

"I hope we can start discussing some solutions as a community so the next generation doesn't have to go through what women before them have, undiagnosed."