Episode 118. Coeliac Disease with Associate Professor Jason Tye Din (Part 1)

First described by Samuel Gee in England in 1887 and Christian Gerter in the United States, the disease of malnutrition and growth retardation now called Coeliac disease was known as Gee-Herter disease. Until the mid-twentieth century, the disease was managed with the so-called banana diet. We now know a great deal more about Coeliac disease, which is recognised as an immune-mediated disorder characterised by chronic inflammation of the proximal small bowel. The inflammation heals with gluten withdrawal from the diet and returns when gluten is reintroduced.

Coeliac disease exhibits significant geographical variation, with the highest incidence in Western Europe and less common occurrences in Asia and sub-Saharan Africa. Once considered rare, with prevalence estimates from the 1950s between 1 in 4,000 to 1 in 5,000, the true prevalence in Western countries, including Australia, is now recognised to be about 1 in 70.

There is a female predominance, and serological testing has demonstrated that silent coeliac disease (no or minimal symptoms with positive serology and small bowel biopsy) is about 7 times more common than a symptomatic disease. Monozygotic twins have a 70% concordance rate. First-degree relatives of individuals with coeliac disease have a prevalence of villous atrophy on small bowel biopsy ranging from 4% to 12%, and there is an increased risk associated with Type I Diabetes and Dermatitis Herpetiformis. Other associated diseases include thyroid disease, Down's syndrome, PBC, and IgA deficiency. The condition should be considered in cases of unexplained female infertility, osteoporosis, and iron deficiency.

Gluten encompasses the storage of proteins from cultivated grasses, including wheat, barley, and rye. After digestion, a wide variety of native peptide derivatives emerge, including the ethanol-soluble component of gluten referred to as gliadins. Gliadin peptides are highly immunogenic, and in genetically predisposed individuals, an immune response within the mucosal lining of the small intestine results in the characteristic injury observed, including mucosal inflammation with increased lymphocytes, crypt hyperplasia, and villous atrophy. Coeliac patients almost universally possess HLA-DQ2 or DQ-8 haplotypes, compared to 20-30% of the general population.

Clinical presentations of coeliac disease may vary from no symptoms to IBS-like presentations and more classic symptoms such as diarrhea, bloating, and weight loss. Osteoporosis presenting at an early age may be the first indication of the disease, as well as unexplained iron deficiency. Less commonly, neurological and psychiatric conditions may be associated, including ataxia, neuropathy, and epilepsy.

Serological studies, including antibodies to deamidated gliadin, tissue transglutaminase, and endomysium, have sensitivity and specificity above 95%. However, their performance may be influenced by IgA deficiency (occurring in 3-5% of coeliac patients) and must be followed by a diagnostic small intestinal biopsy taken proximal and distal to the ampulla of Vater.

HLA ‘gene’ screening for DQ-2 and DQ-8 has applications where there is doubt about the diagnosis. A negative result essentially excludes the diagnosis. However, there is no merit in using this test as a screening tool for coeliac disease, as these HLA antigens are present in 20-30% of the normal population. Thus, out of 100 people of Caucasian ethnicity tested for HLA, 20-30 would show a positive result, yet only one or fewer would have gluten enteropathy.

Treatment of coeliac disease requires lifelong adherence to a gluten-free diet. In Australia, gluten-free labelled products, by law, must contain less than 0.003% gluten. Triticale, Couscous, Spelt, Semolina, and Burghul or cracked wheat are all to be avoided. Rice, corn, buckwheat, tapioca, polenta, and dhal are all permitted for consumption by coeliacs. Beer and whiskey derived from malt, sadly, are not recommended, despite the lack of clear evidence of them inducing mucosal damage. Formal dietetic review and the use of support groups are strongly advised in patient management.

Untreated or inadequately treated coeliac disease is associated with a 20-fold increase in the risk of solid malignancies, including oropharyngeal, oesophageal, and intestinal cancers. Additionally, there is a quoted 80-fold increase in the risk of lymphoma.

I am very interested in inviting Assoc. Prof. Jason Tye-Din to Everyday Medicine to discuss this fascinating subject in more depth. Jason is an active clinician practicing gastroenterology, but he is also a laboratory head in the division of immunology at Melbourne's Walter and Eliza Hall. He is actively involved in researching the inflammatory response to gluten in human participants and characterizing CD4+T cell antibody responses to gluten. His aim is to improve clinical pathways to promote timely and cost-effective diagnosis, monitoring, and management of coeliac disease.

Please join me with Jason Tye-Din over the next two episodes.

References:

 Assoc Professor Jason Tye-Din: www.wehi.edu.au

 Coeliac Society of Australia: www.coeliac.org.au

 Gastroenterology Society of Australia: www.gesa.org.au

 The Dietitians Association of Australia: www.data.asn.au

 Gastronet: www.gastro.net.au

To be a guest on the show or provide some feedback, I’d love to hear from you: manager@gihealth.com.au.

Dr Luke Crantock MBBS, FRACP, is a gastroenterologist in practice for over 25 years. He is the founder of The Centre for GI Health, based in Melbourne, Australia, and is passionate about educating General Practitioners and patients on disease prevention and how to manage and improve their digestive health.