From human genome to global genome - why precision medicine must address genetic diversity
The publication of the first human genome sequence more than 15 years ago marked the start of a new era in medicine. In the years since then, researchers have greatly expanded knowledge of gene-disease links and gained a better understanding of the underlying molecular pathways.
The first precision therapies, targeted to specific molecular alterations, are already available. Despite this progress, the lack of diversity in genetic databases limits the potential benefits and markets for these advances. To further grow the field of precision medicine, much more knowledge is needed of the global diversity found in the human genome.
Incomplete genetic knowledge limits the advancement of precision medicine
It is a well-known fact that most drugs do not make it past the early stages of clinical trials. Even those that do reach the clinic often do not perform as well as hoped – for example, a recent study found that more than half of cancer drugs entered the market without evidence that they improved survival or quality of life (1). And when drugs do work, they do not always work equally well in everyone.
Precision medicine aims to improve the odds of success, getting the right drugs to the right patients in the right dose, saving time and money and ensuring that more people are likely to receive effective treatment (2). These promises are starting to be realised for certain patients where there is a clear link between a genetic variant and the effectiveness of a certain drug. For example, ovarian cancer patients can be helped by the cancer growth blocker olaparib (Lynparza), but this drug only works if the cancer is caused by a pathogenic variant of one of the BRCA genes (3), as revealed by a simple genetic test.
However, there are still many missed opportunities. Precision medicine requires knowledge about specific genetic variants and how they relate to disease. The more common variants – the ones that are studied the most – are the ones most likely to become targets for new drug development. But a common variant in one part of the population is not necessarily common everywhere, and this approach will only be effective if there is a fuller understanding of the different genetic variants across the entire global population.
A recent analysis estimates that 78% of the people whose DNA is included in genome-wide association studies (GWAS) are of European descent, with a similar picture emerging when looking at the overall catalogue of studies carried out to date (4). A further 8% are East Asian, 6% have no reported ethnicity and the remaining 8% represents everyone else – including all of Africa, Latin America, Pacific island nations, the Middle East, Central and South Asia and various indigenous tribes across the world....
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