This smiling little girl is Sacha Skinner. As she innocently gazes at the camera she looks just like any other five-year-old without a care in the world. But Sacha is dying.

She is suffering from an extremely rare condition which means she is unlikely to live beyond 12 years.

Her devastated parents Annette Dacosta and Neil Skinner are desperately trying to raise £10,000 to send Sacha to America for the one experimental treatment which could save her life.

Ms Dacosta, from Brighton, said: "When you have a child born normally who you think is fine, you think she will grow up to drive and get married and go to university. It is heartbreaking."

Two years ago Sacha began developing the symptoms of Batten Disease, a rare but fatal disorder of the nervous system.

She started having seizures and was diagnosed with epilepsy but it wasn't until this summer that the illness was finally confirmed.

Ms Dacosta said: "Sacha was born normally and was a normal child up until December 2003, when she woke up one night with a seizure. Over time, the seizures became more frequent and more and more severe until she was hospitalised in May 2004 for a couple of weeks. There, she was diagnosed with epilepsy and she was given various drugs. However, they were having little effect on her condition.

"With Sacha still failing to respond to the drugs, we took her to a consultant in January this year where Batten Disease was first mentioned as a possibility.

"She had various tests done from there including a blood test which came back as normal and also a skin biopsy in July.

"It was this that conclusively proved Sacha had Batten Disease."

Sacha has already lost most of her vocabulary and is only able to say one word at a time.

She used to be potty trained but has now reverted to nappies and her mother has to carry her up the stairs several times a day.

Despite all this, Sacha doesn't know that she is different from any other child. Ms Dacosta said: "She isn't unhappy or in any pain. She goes to a special school. We try to keep everything as normal as possible for her.

"She has a set routine, starting with breakfast each day just to make sure she stays to a routine."

Sacha's only hope lies in a gene replacement therapy being developed at Cornell University in New York but it will cost £10,000 for the family to live there for a month.

Ms Dacosta said: "Other children have had the same type of Batten Disease as Sacha and none of them have improved. The therapy is not really proven yet because so few children have the disease.

"So far ten children have had the treatment. One's already died but they are not sure whether that was because of the operation or the disease."

Sacha is a strong candidate for the therapy because she is younger than most children who have had it so far.

Researchers hope this will give her a better chance of success. However, she will only be able to receive the treatment if tests show the right sort of gene is affected. If not, even the Cornell treatment will be out of bounds. The only other treatments that can help are the drug Flupirtine being developed in Germany to treat the symptoms and a therapy being developed by stem cell researchers in America which has not yet been licensed by the US Government.

Ms Dacosta said: "We have to start fund-raising. I am looking at holding a benefit concert at Concorde 2 and we want to raise awareness of Batten Disease."

Sacha's father Neil Skinner said: "It has been horrendous for both of us to see her deteriorate. She's my first child so it has been devastating. I'm trying to stay positive and keep myself going by focussing on the treatment options.

"I'm just hoping it's still possible to help her but ten kids have already been through the operation and it's not made any difference so it's a slim chance."

Manchester parent Mark Shone has been helping guide Ms Dacosta and Mr Skinner through the anguish of watching their daughter deteriorate.

His eight-year-old daughter Bobbie was the fourth child to undergo the therapy at Cornell University a year ago but died six weeks later.

Batten Disease is named after the British paediatrician who first described it in 1903.

The illness leads to a deterioration of the brain and nervous system.

Although knowledge of the disease is improving, there is currently no cure or treatment that has any major impact on the decline in bodily functions and inevitable early death.

A number of different forms of the condition have been identified. The disease was elevated to national attention in the Nineties by Rhys Daniels and his sister Charly.

Rhys was the first child to have a bone marrow transplant to try to cure the genetic disease in 1993.

Both children died in 1999.