A runner whose father and grandfather were both afflicted by heart disease is taking on the London Marathon to help those with the condition.

Sam Rhodes' 71-year-old father had a major cardiac arrest last year, leaving him comatose for several days and then with severe short-term memory loss.

His grandfather was killed by a heart attack at the same age and Mr Rhodes has hereditary high cholesterol, leaving the 36-year-old father-of-two susceptible to heart disease.

The customer marketing director, who lives in Isleworth, is running the Virgin Money London Marathon on April 26 in aid of HEART UK, which supports people with inherited high cholesterol and campaigns for better detection and treatment of cholesterol related conditions.

"My father had a major cardiac arrest in August 2014 so I decided I would enter the London Marathon to raise money for a relevant charity," he said. "My father's cardiac arrest left him in a coma for a few days and then with dreadful short-term memory loss for a number of weeks.

"The memory loss was pretty severe and meant he didn't recall having any grandchildren or that my sister had moved to Australia and got married seven years prior.

"My family history of high cholesterol is quite pronounced.

"My grandfather on my father's side suffered a fatal heart attack at the age of 71, my father is currently 71 having had his first heart attack at the age of 41 and then this recent one also at 71 and I too have hereditary high cholesterol – hence my motivation to exercise."

Heart disease is one of the country's biggest killers and six in 10 adults in the UK have raised cholesterol, according to HEART UK, leaving them more vulnerable to the condition.

More than 120,000 people in Britain are estimated to have a form of inherited high cholesterol called Familial Hypercholesterolaemia (FH), which can prove fatal for those as young as 30, yet only 15% of people with the condition have been diagnosed.

You can sponsor Mr Rhodes at http://uk.virginmoneygiving.com/samrhodesmarathon.