Is a real, genetic heritage behind the mythological giants of Northern Ireland? Researchers have found that a cluster of people in Mid-Ulster have a genetic predisposition to grow abnormally tall.

According to scientists, about 1 in 150 people in the region carry a genetic mutation to the AIP gene, going back 2,500 years, that leads to an overproduction of growth hormone resulting in acromegaly, also known as gigantism. The hormone disorder is stimulated by a tumor on the pituitary gland, reports

"This is probably the highest proportion of giants in the whole world in that little part of Northern Ireland," says Marta Korbonits, a professor of endocrinology at Barts and the London School of Medicine Queen Mary.

Korbonits’ research team first discovered the link between the AIP gene defect in Irish populations and gigantism in 2011.

"Humans have about 30,000 genes, and if you imagine that each gene is a book within a library, we have a library with 30,000 books, Korbonits explains. "The one which we're talking about here is called AIP... and the Irish guys have one particular spelling mistake in this book."

The team has most recently found that the defect goes back 2,500 years. They discovered the variant in Charles Byrne, a man born in 1761 who grew to be 7 feet, 6 inches tall and was known as the "Irish giant," as well as in 18 other Irish families

"The disease usually develops in children between 10 and 20, although we have a few cases younger than 10, and some between 20 and 30," said Korbonits.

In children, there is rapid growth that can be accompanied by joint pain, disabling headaches, vision problems, type II diabetes, facial distortion and enlarged hands and feet.

If symptoms develop later in life, adults don't get taller, because their bones are already fused. Adults may in fact shrink due to developing a curvature in the spine. Symptoms may include muscle weakness, hypertension and difficulty sleeping.

"While these people might look big and powerful and strong, the long-term effects of excess IGF-1 and growth hormone are very disabling for these patients," explains Anthony Heaney, endocrinologist and professor at the David Geffen School of Medicine at the University of California, Los Angeles (UCLA).

"We have this fascination with these really large, powerful people, and yet they themselves have a lot of morbidity and potential mortality from this disorder," Heaney continues.

Available treatments include surgery, medication or radiation therapy, but the effectiveness of the treatments those depends largely on how far the disease has already progressed.Early clinical intervention can help prevent the worst of the symptoms, so monitoring the lineage of the gene variant lets researchers keep an eye out for children who inherit the defect, reports.

It is possible the genetic defect has inspired local folklore. Legend has it that the Irish giant Fionn mac Cumhaill created the Giant's Causeway, an interlocking series of basalt rocks stretching across the North Channel, as stepping stones to Scotland, so that he could fight the giant Benandonner. The giant is also credited with creating the Isle of Man when he scooped up a clump of land from what is now known as Lough Neagh to fling at a rival but missed, and the clump landed in the Irish Sea, making the island.