Dad Alan Case plans to run the Bath Half Marathon to raise money for a charity that supported his family when his 18-year-old son Jack underwent treatment for a rare disease.

Jack, of Addington Close, Devizes, had Cushings Disease caused by a benign tumour in his pituitary gland, which in turn over produced a steroid hormone called Cortisol resulting in excessive weight gain.

He was diagnosed last March after five years of being unable to lose weight and not growing in height.

He underwent an operation at Frenchay Hospital, Bristol, last August where the tumour, which was the size of a pin head, was removed.

Since the operation he has lost about two and a half stone and is now just over ten stone. He has also gained four inches in height and is 5ft 4 inches tall.

Jack has to take steriod tablets because his body is not now producing enough Cortisol and his consultant advised him it would take up to a year for him to recover and as a consequence he was told to take a gap year after leaving Devizes School. He intends to go to university to read sports studies. His ambition is to become a primary school teacher.

Jack, who works part time as a chef at Pizza Express in Devizes and is a voluntary teaching assistant at Wansdyke School, said: “I was always quite positive throughout the past few years. The only time I was a little bit down was when I couldn’t go straight to university.”

His weight gain meant he could not play football or other sports to his previous ability because he struggled to run.

When he was 16 his mother, Wendy, took him to slimming classes to see if a diet could solve his weight gain but this was unsuccessful.

Jack and his parents and siblings, Jeff, 19, Amy, 17, and Alfie, ten, were supported by The Pituitary Foundation, a charity based in Bristol.

Jack’s father, who is managing director of a software company, decided to run the Chippenham Half Marathon last September and together with his brother, Stephen, and nephew, Simon Case, and his wife, who sold jewellery that she made, they raised about £2,000 for the charity. It was the first time he had run a half marathon since he was 18.

Mr Case, 44, said: “It was Jack’s idea to raise money for The Pituitary Foundation. He wanted to give something back to them.

“It was hard to get back into running but Jack inspired me to do it. He was going through a lot more than I was.”

Mr Case intends to run the Bath Half Marathon on March 7 although he has not been able to train for a few weeks due to a back injury.

To sponsor him email alan@bullguard.com