The 18th century 'giant', from Northern Ireland, went to London in the 1780's and worked as a 'freak', exhibiting himself as a curiosity. However, after developing a drink problem, he died aged just 22 in 1783.
DNA taken from two of his teeth show that a mutant gene caused tumours on the pituitary gland. The gland, located at the base of the brain, controls growth and tumours can cause abnormal growth such as thickened skin, enlarged hands and feet and overgrown organs.
The scientists, led by a team at The London School of Medicine and Dentistry, noticed that a number of living patients of Irish descent also carried the mutated form of the gene. However, only about 30% of those with the mutation, actually go on to develop the tumours.
Prof. Marta Korbonits, who led the research estimates that between 200 and 300 living people might suffer from the same abnormality today - most located in a small (and secret) area of Co. Derry near where Byrne was born.
The scientists estimate that Byrne and the families had a common ancestor around 1,500 years ago who originally developed the mutation.
Charles Byrne's skeleton remains in a glass case in the Royal College of Surgeons in London. Purchased by John Hunter, a surgeon, after his death, the body was boiled in acid to remove the flesh and he was put on display, just as he had been during his brief lifetime.
Frightened that doctors would try to dissect him after his death, he had requested, on his deathbed that he be buried at sea. Alas, it wasn't to be and according to one contempory report, his death was followed by "The whole tribe of surgeons put in a claim for the poor departed Irishman and surrounded his house just as harpooners would an enormous whale."
Byrne's skeleton now resides at the Hunterian Museum at the Royal College of Surgeons in London.