Genetic link to diabetes found

A gene that causes type 1 diabetes has been discovered, reported The Sun on July 11 2007. “Doctors now hope to test infants for the gene,” the paper explained. Researchers have identified a gene, KIAA0350, that increases the risk of getting type 1 diabetes (insulin dependent diabetes). News reports suggest that this may help in preventing the disease or will be used to develop new treatments.

However, any association between this gene and type 1 diabetes does not mean that researchers would know how to prevent diabetes in children who were found to have these genetic mutations. Diabetes is a complex disorder and the risk of developing it is known to be affected by environmental factors and at least four other genes. The variations discovered in this study therefore will not be responsible for all cases of type 1 diabetes. This means that at the present time, genetic testing of children for these variants is unlikely.

Where did the story come from?

The stories were drawn from a study conducted by Hakon Hakonarsen, Constantin Polychronakos and colleagues at McGill University, Montreal and the Children’s Hospital of Philadelphia. Funding was by the Children’s Hospital of Philadelphia, Ontario Genomics Institute, and the Juvenile Diabetes Research Foundation and it was published as a letter in the peer-reviewed journal Nature .

What kind of scientific study was this? 

This genome-wide association study aimed to identify the genes associated with type 1 diabetes. The study was performed in two stages. The first stage was a case-control study, comparing the DNA of 563 children with type 1 diabetes (cases) with the DNA of 1,146 people without diabetes (controls) looking for differences in the genetic sequence between those people with type 1 diabetes and those without.

In the second stage, the researchers tested to see how the variations that had been identified were passed on in 549 different families with 1,333 children with diabetes. If the genetic variation was associated with the disease, it should be passed from the parents to the children with type 1 diabetes at a rate higher than would be expected by chance.

What were the results of the study?

One new area was found to be associated with diabetes in both the first and second parts of the study. This area, on the short arm of chromosome 16, contained the KIAA0350 gene and no other genes. This gene is active in the cells of the immune system, but it is not yet known what the protein that the gene encodes does.

What interpretations did the researchers draw from these results?

The authors concluded that they had identified a gene that might be involved in the development of type 1 diabetes, and that the technique that they used to find this gene would be useful in identifying other variations associated with other diseases.

What does the NHS Knowledge Service make of this study?

This study was well conducted, and the results are reliable. The authors note that another study has also reported an association between KIAA0350 and type 1 diabetes, which adds weight to their findings. However, identification of genetic variations within the KIAA0350 gene region associated with type 1 diabetes does not necessarily mean that these variations cause diabetes. There are a few other points to bear in mind when interpreting this study:

• Type 1 diabetes is a complex disease, and the risk of developing it is affected by several genes, along with environmental factors. Four other genes that are associated with the risk of type 1 diabetes have also been identified. Therefore variations in the KIAA0350 gene may not be associated with all cases of type 1 diabetes. 
• This study was conducted in families of European descent. It is possible that in other ethnic groups, variations in the KIAA0350 gene that are associated with type 1 diabetes may be less common.
• Knowing that there is an association between this gene and type 1 diabetes does not mean that researchers would know how to prevent diabetes in children who were found to have these variations. The combination of this and the factors mentioned above means that genetic testing of children for these variants at this present time is unlikely.
• Much more research before we will know if whether the protein encoded by KIAA0350 might be a suitable target for diabetes treatments.