Little did the couple know nearly five years later they'd be turning to experts in the US to undertake cutting-edge STEM cell therapy in an effort to treat their autism.

Mrs Donlan carried the boys for 37 weeks in what was a "perfect" pregnancy, and neither she nor her husband had any known history of disability in their families.

The boys were about 12 months old when the couple noticed they were falling behind.

"Everything was normal until then, but at about one year old they sort of stopped developing at all," Mrs Donlan said.

The boys were first diagnosed with delayed development and eventually diagnosed with autism.

Mrs Donlan said their 3-year-old daughter Imogen's development has now surpassed theirs.

"They've started to say a few words, but no real comprehension," she said.

"They'll repeat words they've heard us say but they're not really talking to us."

The Donlans have dedicated many hours to becoming experts in their sons' condition and hours into researching the treatment available to them.

Mrs Donlan said the advice from experts in Australia is that speech therapy and occupational therapy are the primary methods used to treat the condition.

"Basically they tell you to accept that this is what you've got," she said.

In the hope of giving the boys a brighter future, the desperate parents have begun crowdfunding to get the boys STEM cell therapy to "heal the brain" overseas.

"It uses donated cord blood and has had very positive results, plus it's non invasive," Mrs Donlan said.

The US company performs the procedure in Mexico and the cost of treating the boys is $43,000 excluding additional costs including travel.

The Donlan's hope the Go Fund Me page which was set up for the boys last week will reach its target to get them treatment by the end of the year.

Mrs Donlan said the American medical professionals have advised that the full benefits would not be felt until 12-months later, the time the boys are set to start school.

She said, with the treatment, she's hoping to get them into a mainstream school.

"We really feel this could be the difference, to give them the chance at a normal life," Mrs Donlan said.

To support the Donlan's visit Go Fund Me and search for Ben and Josh.