The number of people with a rare genetic disease is growing throughout Aboriginal communities in the Northern Territory and advocates are concerned changes to funding will leave them worse off.

It is estimated more than 500 people in the communities around Arnhem Land and Kakadu are at risk of developing Machado-Joseph disease (MJD).

The degenerative brain disease leaves patients wheelchair-bound and eventually stops them from being able to swallow food.

Researchers suggest the disease is 100 times more prevalent in affected Aboriginal communities than the rest of the world.

MJD Foundation research director Libby Massey says many direct descendants of patients are at risk of developing the condition.

"We would anticipate that in the next generations there's a 50 per cent chance for people with a parent and 25 per cent for people with a grandparent with MJD," she said.

About 90 people to date have a diagnosis or symptoms of the crippling illness in the area and plans had been underway to extend services to cope as the disease progressed in the NT communities.

The former Labor government promised $10 million to the foundation from mining royalties fund the Aboriginals Benefit Account.

The foundation had planned to invest the money in perpetuity to provide long-term funding and to establish permanent services in communities where MJD was growing. At present, it only provides part-time support.

New Indigenous Affairs Minister Nigel Scullion cancelled the grant in February, though the Government is offering the foundation $500,000 a year to cover the loss.

The foundation is worried the change to government funding will remove the flexibility needed to tailor support services for the growing numbers of MJD patients.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 5 minutes 32 seconds 5 m Sufferers of MJD are increasing in numbers in Arnhem communities

Occupational therapist Ellen Christian visits MJD-affected communities about once a month.

"We need local people here on the ground to be employed by the foundation that are here all day, every day," Ms Christian said.

The Government says the spread of disease would be slow and it would be years before there was any dramatic increase in need for support.

Mr Scullion said under the funding change the money going to the foundation each year remained the same.

"The only question can be in three years' time, who's going to be around to ensure that money is rolled over?'' he said.

"Certainly if we're in government we've already made that undertaking."

70 descendants at risk of developing disease

Ngukurr, in southern Arnhem Land, is one of the remote communities in the Northern Territory where the number of people with MJD is growing.

Great-grandfather and elder David Daniels has 13 children and did not know anything about MJD until he was diagnosed in 2009.

The 68-year-old is now wheelchair-bound with slurred speech, and has more than 70 direct descendants in the region who are all at risk of developing the disease.

Relatives of David Daniels gathered in Ngukurr to learn about the effects of MJD. ( ABC News: Michael Coggan )

Sitting in his wheelchair surrounded by family at a barbeque, Mr Daniels told the ABC that "nearly every third one of them got MJD".

Associate professor John MacMillan, a Brisbane-based geneticist with the foundation, visited the community to test people with symptoms and spoke to residents about their potential risk.

He said people with emerging symptoms were often mistaken for being drunk.

"It's hereditary so it runs in families. It's neurological which means it affects the brain and the spinal cord and the main feature is people develop progressive problems with walking," he said.

Isolation of communities helps disease spread

Medical researchers identified MJD among Aboriginal families living on Groote Eylandt, off the Arnhem Land coast, in the 1990s.

Before then, the disorder had been described as Groote Eylandt syndrome and researchers suspected the cause was poisoning from manganese mining on Groote.

Recent research suggests the local variation of the disease originated in China up to 7,000 years ago and could have been brought to Australia by Macassan traders.

Professor MacMillan says isolation has helped to spread the disease among remote Aboriginal communities in the Northern Territory.

He says the isolation means the genetic pool remains small and the likelihood of the disease passing to children is increased.

"The combination of geographic isolation, language isolation, cultural and social isolation, when you add them all together will often result in very high frequencies of specific diseases in some specific areas," he said.

Symptoms appearing earlier in younger generations

Libby Massey helped establish the MJD Foundation on Groote Eylandt in 2008 and says the disease is tending to appear in younger generations earlier.

"We know that we're going to see an acceleration of the amount of people and the age will be decreasing in terms of when they present with symptoms," she said.

Bronwyn Daniels's symptoms started in her thirties while caring for her father, who was not symptomatic until he was in his sixties.

Ms Daniels said she "became weaker and weaker".

"Then I tried to run one part but I couldn't because it started on me, the MJD," she said.

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