New genetic test makes treatment for Crohn’s and Colitis safer

06 March 2019

Research we have funded has led to an exciting genetic discovery that will make treatment for Crohn’s Disease and Ulcerative Colitis safer. 

The study, led by Tariq Ahmad at the University of Exeter, has discovered a gene mutation that will identify people who could be at risk of drug side effects. This will help doctors when they decide the best treatment options for their patients.  

DNA from approximately 500 patients with Crohn’s or Colitis with bone marrow suppression and 680 ‘control’ patients were looked at by Tariq and his team to try and discover other genes linked to this adverse drug reaction.  

In an exciting breakthrough, the researchers found a link between mutations in a gene called NUDT15 and bone marrow suppression.


In the largest genetic analysis into the side effects of thiopurine drugs we’ve discovered variation in a gene that can help us identify who is susceptible to thiopurine-induced bone marrow suppression. Working with patients and clinicians from across the UK, we have shown the power of the NHS to deliver clinically meaningful genetic research outcomes.

Dr Tariq Ahmad
Consultant Gastroenterologist and Chief Investigator, University of Exeter Medical School

Many people with Crohn’s and Colitis are treated with immunosuppressant drugs azathioprine and mercaptopurine (known as thiopurines). However, about 7% of these people develop an adverse reaction to these drugs called 'bone marrow suppression'. This means that the body’s immune system is less able to fight infection. 

In the past, researchers have looked into what might be causing this reaction, and mutations in a gene called TPMT have been identified. If patients carry this faulty TPMT gene, doctors could either choose not to prescribe azathioprine and mercaptopurine or adjust the dose. However, only a quarter of patients who suffer from bone-marrow suppression have abnormalities in TPMT, which suggests other genes may be involved.  


This study could have a significant impact for people with Crohn’s and Colitis, and all it will take is a simple blood test that could prevent them from taking potentially harmful medication. Drug side effects are just as important to consider as initial symptoms, and we are delighted to have funded a study that will mean that at risk patients are not exposed to treatment that could lead to complications.

Helen Terry
Director of Research, Crohn's and Colitis UK

We are only able to fund research thanks to our generous donors and amazing fundraisers. Thank you so much for your support.

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