It's a day mum Sue Jones thought might never come, but as her son Nick celebrates his 21st birthday, the Wiltshire family reflect on his remarkable journey – which took him to Downing Street seven years ago.

Nick Jones, who lives in Corsham, Wiltshire, suffers a rare condition called Tuberous Sclerosis Complex (TSC). It affects just one in 6,000 people.

It means he has epilepsy and can suffer up to 16 fits a day, he has a disfiguring rash on his face and needs a wheelchair to get about.

Mrs Jones, who is keen to raise awareness of the condition, said: "There have been some highs and lows over the past 21 years, but he's still fighting.

"When Nick was first diagnosed, I was overcome with emotion. I was devastated – it seemed the worst illness I'd ever heard described.

"I was shocked and angry at being given no clear prognosis and I felt a sense of bereavement for the son I felt I'd lost.

"We didn't know whether Nick would ever see his 21st birthday, but he has. It's fantastic.

"Nick is a wonderful, funny, loving son. He is a great mimic. He often has us collapsing with laughter."

The family organised a party to celebrate the milestone birthday over the summer.

Not only has Nick developed into a loving young man with a great sense of humour, but his plight has also raised awareness of the potentially life-threatening condition.

In 2001, the family were invited to Downing Street where they met the then Prime Minister Tony Blair, his wife Cherie and son Leo.

The invitation came after Nick's older sister Kate wrote a letter to Mrs Blair about her brother and his illness. They were keen to raise awareness of TSC, which can result in severe learning difficulties and behavioural problems, as well as skin lesions and heart and lung tumours.

The family has also been heavily involved in fundraising for the Tuberous Sclerosis Association (TSA).

Mrs Jones said: "Everyone found it therapeutic to channel their energies into fundraising. It made us all feel less helpless."

Although Nick's behaviour and epilepsy have calmed since his adolescent years, there are new clouds on the horizon. Doctors have discovered potentially dangerous tumours on his kidneys.

On hearing the news, Kate rushed to offer her own kidney should it be needed. For now, however, the family is just enjoying Nick, who continues to keep them busy and keep them laughing.

A spokesman for the TSA, which carries out research into the condition, said: "TSC can be diagnosed at any time, from before birth or as a baby, like Nick, or into adulthood, but can be a real shock for people coming to terms with it in later life. It is a multi-system disorder caused by mutations in TSC genes. It is a difficult condition to understand and cope with, both for those affected and for the people who care for them – family members, friends or carers and medical professionals. It affects people in very varied ways."

The TSA has published a new leaflet for teenagers or adults diagnosed with TSC to help them know what to expect and where to go for support."

For more information visit www.tuberous-sclerosis.org