Scientists are to carry out genetic screening to establish how widespread a "giant" gene is in a rural part of Northern Ireland.
The 1,500-year-old mutated gene, which can cause excess growth in humans known as gigantism, is thought to be particularly prevalent in the area encompassing the southern part of Co Londonderry and eastern half of Co Tyrone.
One historical resident who had the inherited condition was Tyrone man Charles Byrne, the so-called Irish Giant, who in the 18th century grew to over 7ft 6in.
Doctors and scientists from Queen's University in Belfast and Queen Mary, University of London are calling on today's generation to get tested for the gene.
More than two-thirds of people who carry the mutation do not develop the condition or experience any health issues, so they would have no idea they have it.
But some people can experience acromegaly - a condition in which a benign enlargement of the pituitary gland causes excess growth of muscles, cartilage and bones. This can lead to complications, including the loss of side vision and hormone disturbances.
With screening in Cookstown and Dungannon in coming weeks, the academics are hoping to identify carriers so they can access treatment to prevent potential future health issues.
Professor Patrick Morrison, honorary professor of human genetics at Queen's University, said the mutated gene is called AIP.
He said: "It was first identified in 2011 in patients from South Derry and East Tyrone who are living with 'familial acromegaly' - an inherited form of acromegaly or 'gigantism'. People with the gene may not necessarily be tall but they may have other health conditions which could be linked to this altered gene. Anyone who is found to carry the gene will be offered confirmation of the result, follow-up advice and, if necessary, treatment to help prevent future health complications which may result from the condition."
Prof Morrison said the screening involves giving a saliva sample by spitting into a tube. He said: "It is free, takes just 10 minutes and there is no need to book." The screening will take place on February 8 and 9 (8am-8pm) in Tesco car park, Cookstown, and on March 1 and 2 (8am-8pm) in Tesco car park, Dungannon.