Scientists have found a gene that can raise a person's risk of developing type 1 diabetes, it emerged today.
The discovery will lead to a better understanding of how the disease develops, and could provide clues to new methods of treatment.
Researchers have already identified four regions of the genome as risk factors for type 1 diabetes, in which the immune system destroys insulin-producing cells in the pancreas.
The disease affects 350,000 people in the UK, all of whom depend on regular injections of insulin to keep their blood sugar level under control.
Without the injections, levels rise, leading ultimately to coma and death. The illness usually appears in people under the age of 40, most often in childhood.
"If we know the gene pathways that give rise to type 1 diabetes, we hope to intervene early in life with targeted drugs or cell therapies to prevent the disease from developing," said Constantin Polychronakos of McGill University, part of the team that made the discovery, which is published today in the scientific journal Nature.
The researchers looked for differences between the genetic sequences of 563 children with type 1 diabetes and those of more than 1,000 healthy people. They noticed that the diabetic children had a particular version of a gene called KIAA0350, which sits on chromosome 16. The gene is known to be active among immune system cells in the body, though scientists do not know its exact function.
"The role of KIAA0350 needs to be investigated," said Hakon Hakonarson of the Children's Hospital of Philadelphia. "However, a special cell type called a natural killer (NK) cell expresses this gene abundantly, although at different levels based on these gene variants."
Prof Hakonarson said a particular mutation in KIAA0350 may activate the NK cells in such a way that they attack and destroy the body's own cells, particularly the insulin-producing ones in the pancreas, resulting in type 1 diabetes. "A particular version of the gene protects against this inappropriate autoimmune response, while a different version of the gene makes it more likely to happen."
Dr Iain Frame, research manager at the charity Diabetes UK, said: "Whilst we don't know exactly what causes type 1 diabetes, we know it is due to a combination of environmental and genetic factors and that the peak age for diagnosis is 10 to 14 years old.
"Identifying genes that make children more likely to develop type 1 diabetes allows us to understand more about the condition. In time, these findings could enable us to develop more targeted treatments for young people."
Prof Hakonarson added that the new discovery was a direct result of advances in genetic screening technology that allow scientists relatively easily to scan and compare thousands of genomes.
"The genotyping technology we now have available has revolutionised the way we can ask and answer research questions," he said.
"Unlike the previous technology, which was quite limited and dealt largely with relatively rare gene variants, we can now detect common genetic variants that are important in large numbers of individuals, and begin to understand how multiple genes interact in complex diseases such as diabetes."
