Study finds genetic commonality between Celiac disease and Crohn's disease

An international team of scientists has discovered that people with celiac disease and Crohn's disease share a number of common genetic loci. The researchers carried out a combined meta-analysis of genome-wide association study (GWAS) data from two large studies, one on each condition, and identified four 'risk loci' in common - IIL18RAP, PTPN2, TAGAP and PUS10.

Both conditions are described as 'chronic inflammatory diseases of the digestive tract' and are the result of a complex mix of genetic and environmental components. Previous work suggests that people with celiac disease have an increased risk of developing Crohn's and that the two diseases may therefore share a common genetic element.

The researchers claim that their analysis of the two datasets meant that they were able to 'detect shared loci with a relatively small effect' and that 'for many diseases with overlapping phenotyic characteristics, GWAS data is available and joint analysis of GWAS datasets of these related diseases could lead to the identification of many new shared susceptibility loci'.

They concluded that 'additional studies will be necessary to understand the mechanisms by which these variants influence both Crohn's disease and celiac', but that the study 'provides a proof of principle that risk factors shared across related diseases can be identified by directly combining genetic data from clinically distinct diseases'.

Celiac disease is an autoimmune condition in which people have an immune response to gluten - a protein found in cereals wheat, rye and barley - which can lead to irritation and damage to the lining of the small intestine. The disorder can cause a range of symptoms including - gastrointestinal problems, weight loss and the poor absorption of nutrients - and is thought to affect around 1 in 100 people in the UK.

Crohn's disease is a form of inflammatory bowel disease (IBD), which causes ulceration and scarring of the intestine. It can lead to a range of symptoms including - abdominal pain, diarrhoea and weight loss - and is thought to affect around 1 in 1,000 people in the UK. The underlying cause of the condition, however, is currently unknown.

The team consisted of scientists from a number of institutions, including researchers from Barts and The London School of Medicine and Dentistry in the UK, the University of Groningen in The Netherlands, the Broad Institute in the USA, the Université de Montréal and Montreal Heart Institute in Canada.

The findings were published in PLoS Genetics.