BBC News

Scientists testing for Northern Ireland 'giant gene'

media captionDistrict reporter Julian Fowler investigates for BBC Newsline.

Scientists in Belfast want to establish if the genetic blip that saw an 18th Century Irishman sprout to more than seven-and-a-half feet is widespread in the area he was from.

A geneticist at Queen's University has appealed for people whose families originate from the east Tyrone and south County Londonderry areas to take part in screening for gigantism.

Professor Patrick Morrison said they would test DNA for an altered gene that can cause the body to produce too much growth hormone.

He said that most of the people who have the condition do not know they have it and suffer no ill effects.

Doctors from Queen Mary, University of London, are also taking part in the study that looks for a gene called AIP, which causes abnormal growth of the pituitary gland.

The gene at the heart of the study is the one that caused 18th century patient Charles Byrne, born near Cookstown in County Tyrone and known as the 'Irish giant', to grow to more than seven and a half feet tall.

Sophisticated genetic calculations identified that Byrne and the living patients who were found to carry the gene shared a common ancestor, and that the mutation is about 1,500 years old.

It is thought to be particularly prevalent in south County Londonderry and in the east of Tyrone.

While most people who carry the gene do not experience any health problems, it can lead to acromegaly - a condition in which a benign enlargement of the pituitary gland causes excess growth of muscles, cartilage and bones.

This excess growth can lead to other complications, including loss of side vision and hormone disturbances.

It is estimated more than two thirds of those who carry the mutation do not develop the condition and therefore have no idea they have it.

image captionProfessor Patrick Morrison said most of the people with the condition are unaware of it

Prof Morrison said that they would be visiting the area to conduct mobile screening to identify carriers so that they, and their families, can access screening and treatment if necessary, to help prevent potential health problems in the future.

"The particular gene mutation for which people will be screened is for a gene called AIP, which causes abnormal growth of the pituitary gland. 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," he said.

"People with the gene may not necessarily be tall but they may have other health conditions which could be linked to this altered gene."

He said the screening involves giving a saliva sample by spitting into a tube and takes about 10 minutes.

Marta Korbonits, Professor of Endocrinology at Barts and the London School of Medicine Queen Mary, said they have been screening a number of patients from Northern Ireland with acromegaly for the gene.

"We also know, however, that over two-thirds of those who carry the mutation do not develop the condition and therefore will have no idea that they carry the gene abnormality," she said.

"This is why it is important to look at the local general population in the geographical area from where many of the patients originate from.

"Testing in the general public will tell us more about how widespread the condition has become."

Screening will take place on 8 and 9 February in the Tesco carpark, Cookstown, and on 1 and 2 March in the Tesco carpark, Dungannon.