A mother is taking part in a march to Downing Street to call for research funding to help her son live longer.

Sue Berry, from Angmering, near Worthing, is taking part in the Muscular Dystrophy Campaign's Race Against Time march to Downing Street and Whitehall on Tuesday.

The march will be made up of mothers calling for the Government to provide £5 million funding for research into a treatment for Duchenne muscular dystrophy.

The Department of Health provided £1.4 million to start the research but more cash is needed.

Mrs Berry's nine-year-old son Matthew suffers from the muscle-wasting condition, which only affects boys.

He is confined to an electric wheelchair but can stand up or walk short distances on calipers.

Sufferers tend to live into their late teens or early 20s but Mrs Berry believes further research can help Matthew live longer.

Scientists at universities in Newcastle and London are developing a treatment called a "molecular patch", which helps muscles to regenerate.

She said the treatment could help her son live to be a pensioner with minimal disruption from the condition.

She said: "The damaged muscles would never be the same again but he would have a normal lifespan.

People diagnosed with the condition might not even be in a wheelchair if the treatment was used early enough.

"I am fighting to extend the lifespan of my child and others like him. There are 100 boys born with the condition in the UK every year and all we are asking for is £5 million from the Government.

"It is a drop in the ocean for the Department of Health."

Matthew enjoys computer games, drawing and watching television, the same as any other young boy.

Mrs Berry said he was coping well with the condition.

She said: "I found out he had it in 2000.

"I had never heard of it so it came as an incredible shock.

"He's a very intelligent young man and he's coping with his decreased mobility and muscle loss incredibly well."

A spokeswoman for the Muscular Dystrophy Campaign said: "Research into Duchenne muscular dystrophy has reached an exciting phase where we are moving towards the testing of potential treatments in humans."

She said the research was developing a treatment that could bypass the genetic defect that caused Duchenne, allowing the muscle to grow normally, but extra funding was essential if it were to be developed.