A large-scale statistical analysis of DNA from nearly
150,000 people of European descent has identified ten new regions of DNA that
may help us understand the biological processes linked to glucose metabolism
and insulin production in type 2 diabetes.
Around three million people in the UK are affected by
diabetes, and of these 90 percent have type 2 diabetes. Both genetic and
environmental factors contribute to the risk of developing type 2 diabetes,
however, the known genetic variants are only thought to account for around ten
percent of the genetic risk.
In order to develop a better understanding of the genes associated with this condition, scientists pooled together data from two existing
case-controlled studies allowing them to compare DNA from 35,000 people with type 2
diabetes and 115,000 people without the condition. They used statistical
analysis to identify trends in 197,000 SNPs looking
for variations that were more common in type 2 patients.
The researchers initially found variations in eight new
regions of the DNA previously not know to be associated with type 2 diabetes.
They also found variations in two other regions not previously associated with
European populations. Of these ten variations, two were affected by gender, with
one variation being more common in women and the other in men. Each of these
variations was associated with a seven to 13 percent risk of developing type 2
diabetes. This brings the total number of gene regions linked to type 2
diabetes to more than 60.
Although it was difficult to identify specific genes responsible
for the condition, many of these variations were next to genes known to be
involved in increased risk of type 2 diabetes.
Professor Mark McCarthy, from the University of Oxford and a
Wellcome Trust senior investigator on the study, said: 'We see genes involved in
controlling the process of cell growth, division and ageing, particularly those
that are active in the pancreas, where insulin is produced. We see genes
involved in pathways through which the body's fat cells can influence
biological processes elsewhere in the body. And we see a set of transcription
factor genes - genes that help control what other genes are active'.
This study will help researchers decipher the biochemical pathways
involved in type 2 diabetes. Professor McCarthy and his team are in the process
of sequencing the entire genome of 1,400 patients and a control group of 1,400 people in the hope that this will help to pinpoint the exact location
of genes involved in this condition.