Personalised medicine for the privileged few

Eddie Cano-Gamez on the need to make genomics more diverse in an age of personalised medicine.

It is now possible to identify individuals at risk of coronary artery disease, breast cancer or other conditions, based on their DNA.

Eddie Cano-Gamez

What is personalised medicine? Some think of it as science fiction: a world where a single drop of blood can tell us which drugs to take or which diseases to expect.

The truth is that personalised medicine is already here. For instance, it is now possible to identify individuals at risk of coronary artery disease, breast cancer or other conditions, based on their DNA. Those who test positive can begin to change their lifestyle or start preventive treatment. This is thanks to methods which use “genomics” (the study of an individual's entire DNA, their genome) to look for genetic markers of disease. Yet, despite its promise, personalised medicine faces a familiar threat: if we don’t do something soon, only people of European ancestry will benefit from it.

The problem is that genomics relies on data. These data come from the DNA sequences of thousands of individuals, which are used to build a type of genetic “reference map”. If a person is at risk of disease, their genome will differ from this map. However, reference maps differ between populations and today 70% of genetic studies are on Europeans (Caucasians). East Asians are a distant second, accounting for a further 20%.

Particularly worrying is the future of personalised medicine for Africans and Native Americans, who are severely and increasingly underrepresented in these data. There are many reasons for this disproportionate representation. For example, most studies are conducted in countries with a large Caucasian population, like the United States. Also, geneticists often avoid mixed populations because these studies require more complex analysis. The threat here is that the difference between the reference maps we have and those that would represent these underserved populations will produce substantially different and potentially harmful results. 

This situation must change. We can start by including minority populations and fostering international genetic programmes. Many are working towards this. The future, however, is concerning. If we don’t make a conscious effort to make genomics diverse, we will soon live in a world where personalised medicine is only available to a privileged few.

*Eddie Cano-Gamez [2017] is doing a PhD in Genomics at the Wellcome Sanger Institute. He studies how genetic variants affect the immune system. This article appears in the current edition of The Scholar magazine.