Grant Goodwin, 30, from Hamilton in Lanarkshire, died in January after experiencing personality change, memory loss, unsteadiness and visual hallucinations.

He was the first person of his gene type to die of variant CJD.

In the UK, 170 people have died of "definitive" and "probable" cases of vCJD and all of them were thought to have shared a particular gene.

But his father Thomas Goodwin said his son had a different genetic make-up, prompting fears that many other people could have the disease but are not showing any symptoms.

Scientists said his death suggested strains of the disease may have an incubation period that spans decades.

Mr Goodwin said his son may have caught vCJD from the baby food he was fed as a child.

He said: "Grant was a very happy-go-lucky person. He was a bit of a jack-the-lad kind of person, lived life, was a bit of a party animal, loved the good life."

But as the disease took hold, Mr Goodwin's son's personality changed and he became depressed. When he started complaining about pain in his legs and head, his parent's moved him back to Scotland from the Channel Islands.

When he saw his son at the airport, Mr Goodwin took him straight to hospital, thinking he had developed a tumour. He was diagnosed with vCJD.

Mr Goodwin said: "Once the illness set into Grant, the brain cells were slowly getting killed off and he became someone else. He was seeing things, he was paranoid, it was absolutely unbelievable what that illness actually does to people."

A month after being diagnosed, the family were told that their son had a different type of gene type than other victims.

"Professor Peter Rudge came up from London and it was him that told us that Grant was the first with his gene type in the world that's died of variant CJD," Mr Goodwin said.

"I just feel we need to get this out in the open because people need to see the early symptoms."