Genetic study of primary sclerosing cholangitis reveals potential drug target

December 19, 2016

Primary Sclerosing Cholangitis (PSC) is a debilitating rare disease of the liver with no effective treatment. Reported in Nature Genetics researchers from the Wellcome Trust Sanger Institute, Mayo Clinic and their collaborators identify four regions of the genome associated with the disease, one of which is a potential drug target.

A rare disease affecting one in 10,000 people in the UK, PSC is a chronic, progressive disease of the bile ducts that channels bile from the liver into the intestines. It can cause inflammation of the bile ducts (cholangitis) and liver failure, and is a leading cause of liver transplant surgery. Approximately 75 per cent of PSC patients also suffer from inflammatory bowel disease (IBD), but the genetic relationship between the two diseases was poorly understood.

To understand more about what causes the disease, a huge international collaboration was initiated, that studied the genomes of 5,000 PSC patients and compared them with genomes from 20,000 healthy people.

Researchers identified four new regions of the genome that were correlated with PSC risk, one of which demonstrated that the disease is associated with increased levels of a protein called UBASH3A.

Dr Carl Anderson, a lead author from the Wellcome Trust Sanger Institute, said: "From our genome wide association studies we have been able to identify several biological pathways that likely play a role in PSC. We discovered that lower levels of the UBASH3A protein correlate with lower risk of PSC. A drug that could reduce the amount of UBASH3A may thus be helpful in treating people with PSC, so this gives pharmaceutical companies insight into biological systems to target."

The researchers also compared this genetic study with previous large scale studies of IBD. While they found many regions of the genome are associated with both PSC and IBD risk, they found others that were only associated with risk of PSC. This indicates that there are unique aspects to the biology of PSC and that the disease is not simply caused by IBD.

Konstantinos Lazaridis, M.D., hepatologist and co-lead on the study from Mayo Clinic College of Medicine and Science in USA, said: "Looking at PSC and IBD patients, we saw both clinical and genetic differences between the two groups. If we want to understand bowel inflammation in PSC, we need to look at that specifically and compare it with a separate group of IBD patients without PSC, not merge the two groups and look at the average. Our study suggests PSC is a separate disease to IBD, despite the many genetic and clinical commonalities."

Dr Tom Karlsen, from Oslo University Hospital, Norway, said: "This research was only made possible due to the 5,000 patients from who participated in the study, and to the amazing effort from the International PSC study group in recruiting them. This is the largest ever study of the genetics of PSC, and we hope this and ongoing research will help improve the future for people suffering with this disease."
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Notes to Editors:

PSC Support Group/ Welcome to PSC Support, dedicated to helping people affected by Primary Sclerosing Cholangitis

Selected websites

About Mayo Clinic

Mayo Clinic is a nonprofit organization committed to medical research and education, and providing expert, whole-person care to everyone who needs healing. For more information, visit mayoclinic.org/about-mayo-clinic or newsnetwork.mayoclinic.org.

The International PSC study group

The International PSC study group (IPSCSG) was founded in Oslo in 2010. The aim of the IPSCSG is to coordinate PSC research projects between leading institutions worldwide. More than 20 countries are represented (see map) and an alignment of important research topics in PSC means that rather than competition and redundancy, projects are run efficiently and are of a size that allows for robust conclusions to be drawn. Both basic and clinical research groups are represented, allowing for translational research that would otherwise not be feasible. http://www.ipscsg.org/

The Wellcome Trust Sanger Institute

The Wellcome Trust Sanger Institute is one of the world's leading genome centres. Through its ability to conduct research at scale, it is able to engage in bold and long-term exploratory projects that are designed to influence and empower medical science globally. Institute research findings, generated through its own research programmes and through its leading role in international consortia, are being used to develop new diagnostics and treatments for human disease. http://www.sanger.ac.uk

Wellcome

Wellcome exists to improve health for everyone by helping great ideas to thrive. We're a global charitable foundation, both politically and financially independent. We support scientists and researchers, take on big problems, fuel imaginations and spark debate. http://www.wellcome.ac.uk

Wellcome Trust Sanger Institute

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