Scientists find new genetic locations in the human genome for type 2 diabetes

by Barbara Hewitt on May 8, 2017

British scientists are closer to understanding the genetic causes of type 2 diabetes by identifying 111 new chromosome locations (‘loci’) on the human genome that indicate susceptibility to the disease, according to a UCL-led study in collaboration with Imperial College London.

The discovery of 111 new chromosome locations for type 2 diabetes is taking scientists closer to understanding the genetic causes of the disease.

It is already known that people could be more susceptible to type 2 diabetes because of their genes and previously 76 loci in the human genome were known and studied and now researchers from University College London and Imperial College London have found more.

They also found more diversity. In the previous 76 loci very few were found in the African American population where the prevalence of type 2 diabetes is almost twice that in the European American population at 19% compared to 10%.

But of the additional 111 loci identified by the team some 93 or 84% are found in both African American and European populations and only 18 are European specific.

The study used a method developed at UCL based on highly informative genetic maps to investigate complex disorders such as type 2 diabetes and analysed 5,800 type 2 diabetes case subjects and 9,691 control subjects, revealing multiple type 2 diabetes loci at regulatory hotspots across the genome.

‘No disease with a genetic predisposition has been more intensely investigated than type 2 diabetes. We’ve proven the benefits of gene mapping to identify hundreds of locations where causal mutations might be across many populations, including African Americans,’ said lead author, Dr Nikolas Maniatis of UCL.

‘This provides a larger number of characterised loci for scientists to study and will allow us to build a more detailed picture of the genetic architecture of type 2 diabetes,’ he added.

He also explained that in order to be able to conduct the functional studies required in order to better understand the molecular basis of type 2 diabetes they need to identify as many plausible candidate loci as possible.

‘Genetic maps are key to this task, by integrating the cross-platform genomic data in a biologically meaningful way,’ added co-lead author, Dr Toby Andrew of Imperial College London.

The team discovered that the additional 111 loci and previously known 76 loci regulate the expression of at least 266 genes that neighbour the identified disease loci. The vast majority of these loci were found outside of gene coding regions but coincided with regulatory ‘hotspots’ that alter the expression of these genes in body fat.

They are currently investigating whether these loci alter the expression of the same genes in other tissues such as the pancreas, liver and skeletal muscle that are also relevant to type 2 diabetes.

‘Our results mean that we can now target the remaining loci on the genetic maps with deep sequencing to try and find the causal mutations within them. We are also very excited that most of the identified disease loci appear to confer risk of disease in diverse populations such as African Americans, implying our findings are likely to be universally applicable and not just confined to Europeans,’ said Dr Winston Lau of UCL Genetics, Evolution and Environment.

The opinions expressed in this article do not necessarily reflect the views of the Community and should not be interpreted as medical advice. Please see your doctor before making any changes to your diabetes management plan.

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