According to Australian genetics experts, Caleb is one of eight known cases in the world where production of Neurod2, a protein coding gene in the brain, is disrupted or not present.

The condition is so rare it does not actually have a name, nor a prognosis, but in people like Caleb living with the disorder it presents in a similar way to autism and ADHD but with other neurological, behavioural, mobility and physical symptoms as well.

Caleb struggles to walk and even five minutes on his feet can leave him screaming in pain. He has involuntary eye movements that his family and doctors now fear might be 'silent epilepsy', he can become violent and 'blank out', suffers general muscle weakness and exhibits other extreme behaviours.

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He was diagnosed with autism and ADHD when he was three-years-old but mum Michelle Ross and his doctors felt there was more going on and genetic testing was carried out.

After several different rounds of tests over two years, they finally learnt Neurod2 had been detected but it left them with as many questions as it gave answers.

Mrs Ross is now desperate to try to contact other families with a child diagnosed with Neurod2 for support and insight in to Caleb's future.

"All he wants to do is get out there and play and be a kid and he can't," she said.

"It's so heartbreaking but I just want to try and find other families and see what they have been through with their kids and what we may be facing in the future."

Currently only a small amount of research has been done in to Neurod2 in mice so little is known about the syndrome, which she first saw signs of when he was just a few months old.

"We had issues with head-banging and things like that since he could roll - he used to roll to stuff to bang his head. We took him to a paediatrician straight away to get help because something was wrong as a baby should not be doing this," Ms Ross said.

He also suffered severe reflux and other problems as a baby, and doctors ordered an MRI to check for brain tumours or other abnormalities but they were all clear.

Then came the diagnoses of autism and ADHD.

"But he had so many more issues that just don't add up to that diagnosis or fit in, so his neurologist and paediatrician recommended genetic testing to see if they could find anything else or find anything underlying that was not getting picked up."

Neither Ms Ross nor Caleb's father carry any signs of Neurod2, which means it has occurred spontaneously in Caleb.

"There are only about eight people with this in the world and there's no official diagnosis and very little information," she said.

Ms Ross has joined the support group Syndromes Without A Name (SWAN), contacted Genetics Victoria and other genetic counsellors in Sydney but none know of any other cases in Australia.

So she has setup a Facebook page Caleb's Journey Rare Genetic Condition Neurod2 in the hope that any other families around the world searching for Neurod2 information might contact her.

Having watched the condition progress in mice, doctors expect Caleb will start having seizures but Ms Ross thinks they might already be occurring as silent seizures with his involuntary eye movement and blanking out.

"They said he will decline over his life. He struggles already with education so he has a helper at school and we get his weekly tutoring to try to help and I do as much as I can with him at home," Ms Ross said.

"He gets in extreme amounts of pain walking for less than five minutes - he'll scream in pain because his legs hurt, his feet hurt, he falls over constantly and has an aide with him at recess and lunch at school because of his mobility issues."

Even going to the supermarket Caleb has to ride in the trolley.

"We are trying to get a pram or wheelchair for him through the NDIS because we can't go out and do much as he's in too much pain," Ms Ross said.

"It's so heartbreaking to see him in so much pain. We are doing physio and occupational therapy to try and help, and he has a massage every two weeks, but there's only so much we can afford.

"We have no idea what's going to happen and what his future looks like which is so stressful and heartbreaking."

NDIS also provides a support worker, but only for two hours a week though Ms Ross is asking for a review for more funding.

That two hours allows Ms Ross to spend some one-on-one time with Caleb's sister Jess, 8, who also has special needs, as she gets ready for school.