A desperately-ill four-year-old girl is hoping to be chosen as one of only ten children in the world to undergo a radical new treatment.

Holly Clarke, who turns five on Thursday, is battling the killer Batten's Disease.

The illness leads to the deterioration of the brain and nervous system causing seizures, blindness, loss of muscle co-ordination, mental deterioration and dementia.

A cure has not been found for the rare disease but a new treatment being pioneered in the United States has given hope to Holly's parents, Darren and Shirelle, of Derwent Road, Bolton, Bradford, who today heard their daughter could be one of the youngsters to take part in the first clinical trials in New York.

But first she will have to undergo a series of tests to ensure her suitability for the treatment.

Shirelle, 34, said: "There is a chance that giving Holly this now will give her a better quality of life. No-one is promising that she will get better but it will hopefully stop the disease. If it doesn't work she will not have lost anything."

Holly has already lost her speech, her eyesight is fading and she cannot walk unaided.

"This has given us a lot of hope and is giving Holly a chance of life," said Shirelle,.

"It will hopefully give us more time with her. She will not get any worse, just older, which is a luxury."

Shirelle and Darren found the ground-breaking gene therapy after spending hours trawling the internet.

The research is being run through the American-based Nathan's Battle Foundation, which was set up by Phil and Tricia Milto to help develop therapies for Batten's sufferers after their sons, Nathan, nine, and six-year-old PJ were diagnosed with the killer disease.

In 2000, the foundation initiated a formal project with Cornell University's Weill Medical College to develop a treatment and initiate a clinical trial of the gene therapy programme which has been tested on hundreds of animals and is now being trialed on humans for the first time.

The treatment works by injecting a "functioning" gene into the brain, which produces an enzyme missing from children with Batten's, thus allowing the brain to function normally.

Mr Milto said: "Our hope is that Holly would be suitable for inclusion in the trial but until she is screened by the team at Cornell we will not know.

"This is the only current hope for a child currently diagnosed with this dreadful disease and just like the Clarkes, as parents we must do everything to help these innocent children. By supporting this cause we hopefully will be saving children's lives and hopefully Holly Clarke's."

Holly will undergo a series of tests in New York to ensure no other illness is contributing to her symptoms.

If cleared, she will join nine other youngsters for the trial, which involves an operation and 18 months of assessment and evaluation.

Mr Milto said: "The goal of the trial is to first prove the drug is safe and then to stop the progression of the disease. So seeing no additional degradation of the child would mean that the drug stopped the illness progressing.

"Some other data has suggested that it is possible that the child could also potentially regain some functions once the disease is stopped by allowing the brain to compensate for losses."

The drug has already worked in all the rodents and primates on which it has been tested.

Darren, 33, said: "We are ecstatic. It's like a big ray of hope. Holly is on top form. She is laughing a lot more now and she is trying to walk.

"As far as we know this will not reverse any damage but it stops the disease in its tracks. This is the best birthday present ever."