Professor Marta Korbonits with the skeleton of the 'Irish Giant', Charles Byrne and Brendan Holland, who has the same gene

A race of giants may have sprung from a mutant gene that first emerged around 1,500 years ago and causes uncontrolled body growth, scientists believe.

The "gigantism gene" was identified in the DNA of an 18th century man known as the "Irish Giant" who stood almost eight feet tall.

Copies of the same mutation have been found in living patients suffering from gigantism and other symptoms of over-growth.

Scientists writing in the New England Journal of Medicine said they suspect all inherited the gene from the same common ancestor who lived up to 66 generations ago. Around 200 to 300 people may be carrying the same mutation today.

The Irish Giant was Charles Byrne - also known by his stage name O'Brien - born in Littlebridge, Northern Ireland, in 1761.

In the 1780s he found fame exhibiting himself as a curiosity or "freak" in London. Despite claims that he towered more than eight feet tall, skeletal evidence shows his height to have been just over seven feet seven inches.

Celebrity life eventually got the better of Byrne, who took to drink and died at his home in Charing Cross aged just 22.

After his death Byrne's body was acquired by the 18th century surgeon John Hunter, and his skeleton remains at the Hunterian Museum at the London headquarters of the Royal College of Surgeons.

British and German scientists conducting the new research extracted DNA from two of the Irish Giant's teeth.

They discovered a mutant version of the aryl hydrocarbon-interacting protein gene (AIP) which matched those found in living patients from four Northern Irish families.

PA