Study finds gene function that protects against type 2 diabetes

An international research study led by researchers from the Universities of Helsinki and Oxford has identified a genetic variant that protects against type 2 diabetes.

Type 2 diabetes affects over 1.1 million Australians and more than 400 million people worldwide so understanding the genetic causes and links is important to future healthcare.

One of the genetic factors associated with type 2 diabetes is a variation in a gene called SLC30A8, which encodes a protein which carries zinc. This protein is important, because zinc is essential for ensuring that insulin has the right shape in the beta-cells of the pancreas.

Researchers have known for many years that changes in this gene can reduce the risk of getting type 2 diabetes, but not how or why it happened. Researchers recruited members from families with a rare mutation in the SLC30A8 gene to join a study to test how they respond to sugar in a meal.

A strength of this approach is that the researchers could study entire families and compare people with the mutation with relatives who don’t have it, but who have similar genetic background and life-style.

Dr Tiinamaija Tuomi, who co-led the study said, “This way, we could make sure that the effects we were seeing were definitely because of this gene, and not because of another genetic or life-style factor.”

Results showed that people with the mutation have higher insulin and lower blood sugar levels, reducing their risk for diabetes.

An international collaboration of 50 researchers also studied pancreatic cells with and without the mutation in the lab, and carried out experiments in mice and human cellular material to understand exactly what was happening when the function of the SLC30A8 gene changed.

Dr Benoit Hastoy, from Oxford Universities Centre for Diabetes, Endocrinology & Metabolism, said “We found that this mutation had collateral consequences on key functions of pancreatic beta cells and during their development.”

“Importantly, this study exposes the extraordinary molecular complexity behind a specific gene variation conferring risk or protection from type 2 diabetes.”

“Taken together, the human and model system data show enhanced glucose-stimulated insulin secretion combined with enhanced conversion of the prehormone proinsulin to insulin as the most likely explanation for protection against type 2 diabetes.

Better understanding of the genetic and pathological mechanism behind diabetes can open up new ways of preventing or treating type 2 diabetes.

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