A teenager who is just one of a handful across the country with a rare brain condition has defied the odds to celebrate his 17th birthday.

North Norfolk News: Sally Fletcher sings for the music video of Colours of Your Rainbow which she has recorded for her son Ben. Picture: Benjamin T.M.F/YouTube.Sally Fletcher sings for the music video of Colours of Your Rainbow which she has recorded for her son Ben. Picture: Benjamin T.M.F/YouTube. (Image: Archant)

Mother-of-three Sally Fletcher from Aylsham was told by doctors her four-month-old son, Ben, had brain damage from birth trauma.

But in the space of the year, Ben also went blind, needed major brain surgery and was later diagnosed with the rare degenerative brain disorder Canavan disease.

North Norfolk News: Sally Fletcher has written a song about Ben. All proceeds will go to Canavan disease charities. Picture: Sally FletcherSally Fletcher has written a song about Ben. All proceeds will go to Canavan disease charities. Picture: Sally Fletcher (Image: Archant)

Mrs Fletcher, 45, said: "The doctor said there was more chance of us winning the lottery than having a child with Canavans.

"At that point we had previous bits of information that he was disabled and then blind. Now they were saying he was going to die. Having a baby is a wonderful thing, and it was being taken away from us piece by piece. There was nothing to console us and there was no research, no cure and no treatment."

North Norfolk News: Ben Fletcher with his parents Sally and Adrian. Picture: Sally FletcherBen Fletcher with his parents Sally and Adrian. Picture: Sally Fletcher (Image: Archant)

Doctors told the family children with Canavan, which affects mobility and causes seizures, die before the age of four.

Mrs Fletcher said: "He was 18 months at this point and we were being told he had lived half his life - it was such a gut wrenching, awful thing to hear."

North Norfolk News: Ben Fletcher is turning 17 and will celebrate his birthday with loved ones. Picture: Sally FletcherBen Fletcher is turning 17 and will celebrate his birthday with loved ones. Picture: Sally Fletcher (Image: Archant)

"The diagnosis was absolutely the worst thing in the word and I wouldn't wish it on anybody. We have had some hard times although we have a lot to be grateful for, lots of love and happiness.."

Today Ben, who is cared for by the Norfolk and Norwich University Hospital, James Paget University Hospital and Addenbrookes in Cambridge, will celebrate his 17th birthday.

Mrs Fletcher said: "He is just pure human spirit and loves being around his mum, dad and family. His severe physical difficulties means he is not able to explore the world so much, but he is so intelligent."

Now Mrs Fletcher has been inspired by her musical background to raise awareness around the disease.

She has recorded a song about Ben - which was mastered at Abbey Road in London - with all proceeds donated to Canavan research charities.

Mrs Fletcher said: "I want people to know there are things to celebrate and look forward to - Ben has been on holiday, climbed a hill side and been to Euro Disney. He has shown me things I could have never known."

Colours of Your Rainbow by Sally Fletcher is on Spotify, Apple Music and YouTube.