A Brisbane father diagnosed with a terminal neurological disease fears he will "wake up dead one day with no assistance" after being rejected for Commonwealth financial help.

Last year, 46-year-old Brett Kelly was diagnosed with Huntington's disease, a rare genetic disease which affects about 1,800 Australians.

As a result, he suffers from continuous involuntary movements, cognitive issues, tremors, depression, and anxiety.

"It's very hard. There's a sway and the constant rocking which is certainly irritating, especially when you're trying to get to sleep at night," he said.

Despite his diagnoses, Mr Kelly said he recently received letters telling him he did not meet the criteria for the disability support pension or the National Disability Insurance Scheme (NDIS).

"I've been approved for a 'disability house', so obviously the Queensland Government considers me disabled enough to get a house, but the Federal Government doesn't think I meet their disability claim," Mr Kelly said.

"I'm just worried I'm going to wake up here dead one day with no assistance," he said.

The condition has plagued Mr Kelly's family for generations.

His 69-year-old mother died from Huntington's disease last year after spending the final five years of her life in a nursing home.

The same disease killed his uncle and grandfather.

Mr Kelly's three children now have a 50 per cent chance of inheriting the disease.

Brett Kelly and children Daniel, aged 7, and Liam, 3. ( ABC News: Louisa Rebgetz )

'Cross between dementia, Parkinson's disease and motor neurone disease'

The former security guard said the symptoms had a huge impact on his life as a single dad.

"I don't like people seeing me and judging me because I saw my mother go through the exact same thing. I saw the other reactions of other people to her in public," he said.

Symptoms for Huntington's disease generally appear between the ages of 30 and 55, with a life expectancy of 10 to 25 years following diagnosis.

Huntington's Queensland CEO Jan Samuels said it was a devastating illness for sufferers.

"It's often described as being a cross between dementia, Parkinson's disease and motor neurone disease all at once, so it's a pretty nasty condition," she said.

She said the organisation was supporting several people in the same situation as Mr Kelly.

"They are being rejected by one part of the system but are unable to access another part of the system and they really are falling through the cracks."

Brett Kelly watched his mother struggle with Huntington's disease. ( ABC News: Louisa Rebgetz )

The stress of finding work

Mr Kelly said he had to attend regular job interviews in order to keep receiving unemployment benefits, but that he felt "disgusting" when being assessed by employers.

"It's hard enough just to motivate myself to shower once a week let alone bloody trying to get up and go to a job every day," he said.

Local community volunteer Desley Griffiths delivers food to Mr Kelly and his family on a weekly basis.

She said Mr Kelly suffered horrendous stress by being forced to attend regular job interviews.

"I have seen him deteriorate, his involuntary movements have become a lot more severe," Ms Griffiths said.

"It just makes you wonder who might be eligible if somebody with his kind of disability, and a terminal illness, is not."

In a statement, Department of Human Services general manager Hank Jongen said they were trying to work with Mr Kelly.

"We understand that this is difficult time for Mr Kelly and we are working closely with him to ensure he is receiving the most appropriate support and payments," he said.

Mr Jongen said the department received 100,000 disability support pension claims a year, but 70 per cent of people were rejected for not meeting eligibility criteria.

"Less than 20 per cent of DSP appeals resulted in the original decision being changed," Mr Jongen said.

The NDIS will provide Australians under the age of 65 who have permanent and significant disability with the reasonable and necessary supports they need to live an ordinary life.

In a statement, a spokesman for the NDIS said a person must meet the disability requirements specified in the NDIS Act.

"For privacy reasons, the NDIA [National Disability Insurance Agency] cannot comment on individual access decisions," the spokesperson said.

Mr Kelly said he would appealing against both decisions.

Insurance lawyer Paul Watson said the support issue was not limited to Huntington's disease.

"We're seeing the vast majority of disability support pension applications rejected. The guidelines are just too harsh," he said.

"There are instances where someone who is a paraplegic could not be entitled to the disability support pension in certain circumstances.

"People who are often profoundly disabled are having their claims rejected, often for technical reasons, and it's really unfair."