Alan Trussler is stepping out to raise thousands of pounds towards research into his grandson's rare medical condition.

Scott Trussler was born with tuberous sclerosis, a genetic condition where tuber-like growths form on the brain and other organs.

The disease is usually detected in childhood and can have a severe impact on learning and development.

Scott first showed signs of the disease when he started having epileptic fits shortly after he was born.

Now he is one, his family are anxiously waiting to see if his condition deteriorates.

Mr Trussler, 52, from Worthing, is planning to raise as much money as possible for the Tuberous Sclerosis Association by taking part in a sponsored walk across the Downs.

He said: "Not too much is known about this condition and although research is being carried out, much more is needed, which is obviously very expensive.

"Although to date Scott appears to be developing normally, this is likely to change with age following the pattern of his condition.

"I am very keen to do my bit to help which is why I arranged the walk."

Mr Trussler, a retired Sussex Police sergeant, will walk more than 100 miles along the South Downs Way, from Winchester to Eastbourne.

He keeps fit by playing squash, swimming and dog walking and is also a member of a hill walking club.

Mr Trussler is being backed all the way by Scott's parents, Rhona, 27, and Derek, also 27, from Worthing.

More than half of people diagnosed with the condition have developmental problems, ranging from mild areas of difficulty to severe disability.

Other potential problems include autism, Asperger's syndrome, attention deficit disorder and hyperactivity.

However, there are also many people with the condition who have no symptoms at all.

Tuberous sclerosis is probably more common than thought, partly because there are people who remain undiagnosed because they are symptom free.

It is thought to affect about 8,000 people in the UK.

The walk is taking place next month and anyone interested in sponsoring Mr Trussler can call him on 01903 241445.