Clopidogrel genetics study - Barts Charity
Scientist pipetting sample into a vial for DNA testing

Genetic study shows that common heart drug may not be effective for a high number of British South Asians

A new study highlights the importance of a more inclusive approach to drug testing, to ensure that it is effective across different ethnicities. 

  • Date: August 22, 2023

Rates of cardiovascular disease for people of South Asian ancestry in East London are high. Researchers used genetics to determine that, for many British people of Bangladeshi and Pakistani heritage, a common heart disease medication may not work.  

Treating heart attacks

Risk of heart attack is widely treated with the commonly prescribed drug clopidogrel, a medication that decreases the risk of having another heart attack after an initial one. To be effective, the drug needs to be activated in the body. However, a new study led by researchers at Queen Mary University of London reveals that, for many British South Asians of Bangladeshi and Pakistani ancestry, this medication is ineffective. The researchers highlight the importance of genetic testing to determine who can benefit from clopidogrel after a heart attack and how doing so could help reduce health inequalities. 

Using genetics to find the right treatment

How patients respond to medication can vary. Some patients will suffer side effects while others might not experience the full intended benefits. This variability in response to medication can be due to a person’s genetic makeup. Using information about genetics to inform prescribing can optimize the benefits of medications and minimize the risk of side effects.  

New researchpublished in the Journal of American College of Cardiology Advances (JACC) and led by Clinical Research Fellow Dr Emma Magavern, suggests that many British people with Bangladeshi and Pakistani ancestry may not fully benefit from clopidogrel. This is due to a gene variant. 

Researchers examined the health data of 44,396 British people of Bangladeshi and Pakistani ancestry in the Genes & Health cohort who gave their consent to link their genetic data with their long-term health records. Of that cohort, 57% were found to have a common genetic change in a gene which is needed to activate clopidogrel and allow it to work. The study also highlighted that more than 2-in-3 British South Asians who were part of the Genes & Health cohort and suffered a heart attack, had been prescribed clopidogrel. 

Studies of European populations show that 30% of individuals have genetic variants that reduce or prevent activation through the production of an enzyme called CYP2C19. 

People of South Asian ancestry have high rates of cardiovascular disease, but previous studies have not looked for these gene variants within UK South Asian populations or linked these variants with the effectiveness of prescribing clopidogrel to reduce risk of recurrent heart attack. 

Using the participants’ long-term health data, the research team was able to show that people with two loss of function CYP2C19 variants were more than three times more likely to have recurrent heart attacks, which may relate to clopidogrel treatment failure. 

Clopidogrel has been shown to prevent heart attacks mainly in people of European ancestry. For the first time we show that genetic variants that render clopidogrel ineffective are present at much higher rates (57%) in people of Bangladeshi and Pakistani ancestry and are linked with higher risk of having another heart attack. This study highlights the importance of using genetics to determine who can benefit from clopidogrel after a heart attack, and how not doing so is likely to disproportionately disadvantage particular ancestry groups, such as South Asians.
Dr Emma Magavern, lead researcher

Our commitment to excellent cardiac care

This study was made possible by Barts Charity awarding over £10m to support the creation of the Barts Heart Centre in 2013.  Part of that award was used to fund talented researchers like Dr Magavern, evidence of our commitment to supporting patient-focused research that leads to better healthcare for all in our diverse East London population. With high rates of cardiovascular disease in the East London South Asian community, we are therefore pleased to see the outcomes of this important study which has potential to lead to more effective treatment for this group.   

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