Genetic defects and carbohydrate malabsorption lurking behind irritable bowel syndrome

A new study, led by researchers at CIC bioGUNE, suggests genetic defects in carbohydrates digestion may be (mis)diagnosed as IBS in some patients.

Researchers at CIC bioGUNE, a member of the Basque Research & Technology Alliance (BRTA), report that congenital sucrase-isomaltase deficiency (CSID) may be misdiagnosed as irritable bowel syndrome (IBS) in some patients.

IBS is the most common gastrointestinal disorder, affecting more than 10% of people worldwide with symptoms including abdominal pain, gas, diarrhoea and constipation. What causes IBS is largely unknown, which hampers the development of effective treatment for many patients.

In their work published as a Letter in the journal Gut, an international team co-led by Ikerbasque Research Professor Mauro D’Amato at CIC bioGUNE studied an adult with a long history of IBS and found mutations in the gene coding for sucrase-isomaltase (SI), the enzyme responsible for the digestion of dietary sucrose and starch. Further examinations, including measuring SI enzymatic activity in the patient, his partial response to a sucrose and starch reduced diet, and a total remission after enzyme replacement therapy with sacrosidase, led the team to revise the diagnosis from IBS to CSID.

“CSID is a rare condition caused by genetic defects in the SI enzyme, which lead to carbohydrate malabsorption due to maldigested sucrose and starch. These molecules accumulate in the lower bowel, where they are fermented by bacteria causing diarrhea, abdominal pain and bloating”, explains Mauro D’Amato.
Previous research by the team had also shown that defective SI variants increase the risk of IBS, hence genetic alterations of this enzyme may have a broader role across a wider range of clinical manifestations ranging from mild(er) IBS to severe CSID.
“In a small fraction of IBS patients symptoms might be due DNA changes in the sucrase-isomaltase gene, and these can be detected by modern sequencing techniques at relatively low cost. The availability of effective treatment options for these patients (SSRD or enzyme replacement therapy, ndr) suggest their genetic profiling may be sought especially when dietary factors appear to trigger symptoms” proposes Mauro D’Amato.

Publication
https://gut.bmj.com/content/early/2021/10/06/gutjnl-2021-326153

About CIC bioGUNE
The Centre for Cooperative Research in Biosciences (CIC bioGUNE), based in the Bizkaia Technology Park, is a biomedical research organisation conducting cutting-edge research at the interface between structural, molecular and cell biology, with a particular focus on studying the molecular bases of disease, for use in the development of new diagnostic methods and advanced therapies.

About the BRTA
The BRTA is an alliance made up of 4 collaborative research centres (CIC bioGUNE, CIC nanoGUNE, CIC biomaGUNE and CIC energiGUNE) and 12 technology centres (Azterlan, Azti, Ceit, Cidetec, Gaiker, Ideko, Ikerlan, Lortek, Neiker, Tecnalia, Tekniker and Vicometch), with the aim of developing advanced technological solutions for Basque companies.
With the support of the Basque Government, the SPRI Group and the Provincial Councils of the three regional provinces, the alliance seeks to promote collaboration among its centres, to strengthen the conditions to generate and transfer knowledge to companies, thereby contributing to their competitiveness, and to spread Basque scientific and technological capacity.
BRTA has a staff of 3,500 professionals, accounts for 22% of the Basque Country’s R&D investment, generates an annual turnover of over EUR 300 million and files 100 European and international patents per year.

About Ikerbasque
Ikerbasque - the Basque Foundation for Science - was set up on the initiative of the Basque Government Department of Education to strengthen the commitment to scientific research by attracting, bringing back and consolidating researchers of excellence from all over the world. Today, Ikerbasque is a consolidated reality, with 290 researchers working in all fields of knowledge.