A recent publication (1) reported the identification of another ten genes which may predispose to type 2 diabetes (T2DM), bringing the current total to around fifty. However, the impact of these genetic studies from a clinical perspective remains minimal. Forty years after the discovery of the first genes involved in diabetes susceptibility, should we be querying the value of expensive ‘factory floor’ genetics?
A major justification for studies is that new genes will allow for the development of new treatments. Whilst it is true that two of the associated genes (known as PPARG and KCNJ11) are targets for diabetes therapies (glitazones and sulphonylureas respectively), this knowledge has not led to bespoke prescribing; every guideline still recommends initial treatment with metformin. Furthermore, the drug classes had been discovered years before the genes were identified.
A second justification is that identification of genetically at-risk individuals will facilitate the identification of environmental influences which are important in disease development. Whilst this may be of great value in type 1 diabetes, it does not really apply in T2DM where we have a pretty good understanding that diet and weight-gain on the background of a sedentary lifestyle will promote the condition. Add in knowledge of a family history of diabetes and it is difficult to imagine that an individualised genome-wide scan will impart much more information. And that’s before cost is taken into account…
Professor Steve Bain