Unlike most little boys his age, Benedict McAlister has never been able to run.

Instead he has to walk about on his tiptoes because his contracting muscles mean he can't put his heels down on the floor.

Benedict, six, was born with Ullrich congenital muscular dystrophy, a rare condition for which there is no cure.

The youngster's parents Justine and Bruce, 41, will have to watch as their boy's muscles continue to weaken and waste over time.

Frustratingly, scientists are in the very early stages of developing a drug that could potentially stop the process of degeneration.

However red tape is likely to slow the research down, which means they are still a long way off from bringing the drug to the clinical trials stage.

The drugs are also likely to be very expensive, sparking more concerns that health bodies may refuse to fund them.

The McAlisters are now backing calls from the Muscular Dystrophy Campaign to make access to these types of drugs easier.

Mrs McAlister 41, from East Grinstead, said: “Benedict's condition is starting to affect him more and more as he grows.

“He cannot run, climb stairs or get up from the floor.

“Benedict is gradually realising that there is something different about him; as a parent this is heartbreaking to watch.

“Scientists are now developing a promising technology that could lead to a treatment for my son's condition.

“The earlier we are able to treat him, the more likely we are to stop further damage to his muscles.

“It would be devastating to see funding issues and red-tape around the assessment of drugs to prevent therapies from reaching our children.”

Mrs McAlister, who has two other children, Sebastian, 12 and Nancy, nine, took Benedict to meet charity representatives, other families and MPs at the House of Commons for launch of a major inquiry into access to rare disease drugs.

It follows a report compiled by the All Party Parliamentary Group for Muscular Dystrophy.

MPs fear convoluted drug assessment processes, funding issues and lack of specialist care could delay, or even prevent entirely, new therapies from reaching children and young people.

They are particularly concerned that funds previously ring-fenced for rare diseases have now been merged into the overall budget for NHS services commissioned in England.

This leaves expensive therapies for rare conditions competing for funds with medications for more prevalent conditions, such as diabetes or heart disease.

Muscular Dystrophy Campaign chief executive Robert Meadowcroft said: “For decades families have battled to raise funds for pioneering research.

“We are concerned that as breakthrough treatments emerge, poor planning at this stage could stall - or prevent entirely - successful treatments from reaching those who need them.

“The NHS must also work to ensure that all patients have access to the right specialist care before treatments become available, or risk families enduring long delays before they can be administered.”