New studies shed light on genetics of diabetes

A series of newly released studies have made major inroads into the understanding of the genetic basis of type 2 adult onset diabetes. Four teams of researchers, from a mixture of academic and private institutions in the UK, America and Iceland, have uncovered seven genes thought to be involved in the aetiology of the disorder. A number of the same genes were identified independently in different studies, lending great weight to the validity of the data.

Type 2 diabetes, a disorder defined by an inability to regulate blood glucose levels, has long been understood to be a polygenic disease. The new findings, published online in the journals Science and Nature Genetics, bring the total number of genes linked to type 2 diabetes to nine. Whilst this research is a long way from helping the 170 million people worldwide affected by the disorder, the sheer number of unsuspected genes implicated points to completely undiscovered pathways, which should provide multiple drug targets for the pharmaceutical industry to take aim at. In the short term, a powerful predictive test to look at an individual's risk of developing the disease is already in development.

The genes were uncovered via the analysis of SNPs, 10 million of which lie scattered throughout the genome, both within and between genes. SNPs are sites of common genetic variation within the genome; the story emerging from Type II diabetes is one of multiple variant genes - with the variance being conferred by SNPs - each with a modest effect on diabetes.

These findings follow closely on the heels of a glut of reports uncovering multiple disease genes in disorders as diverse as prostate cancer and autism. They are the first successes of 'whole genome association' studies performed in collaboration with multi-country public resources such as HapMap, which hold online banks of SNP data from which researchers can search for genes that affect health, disease, and individual responses to medications and environmental factors.

The aim of whole genome association studies is to perform large-scale genetic analysis on large batches of patients who have been extensively characterised in clinical studies. This type of study has become possible in the wake of the Human Genome Project and promises to yield many exciting results. An imminent report by the Wellcome Trust Case Control Consortium, one of the groups involved in the latest research, is using the same technology to look at seven different diseases, including cardiovascular disease and schizophrenia.