Dr Tye-Din said the new approach of combining the genetic test with a panel of antibody tests would increase the accuracy of testing, decrease overall medical costs by reducing invasive diagnostic tests, and avoid medically unnecessary use of a gluten-free diet. “Currently, bowel biopsies are recommended for anybody with positive antibody tests,” he said. “In this study the inclusion of a simple genetic test helped identify a substantial number of people whose antibody tests were falsely positive and who did not actually require a bowel biopsy to test for the possibility of coeliac disease.” Coeliac disease is caused by an inappropriate immune response to dietary gluten. Gluten can be found in wheat, rye, barley and oats. When gluten is consumed, it can cause a wide range of complaints from chronic tiredness, iron deficiency, osteoporosis, itchy rash, and headaches to various digestive symptoms. Coeliac disease damages the lining of the small intestine and can lead to significant medical complications such as autoimmune disease, infertility, liver failure and cancer. Coeliac disease usually develops in childhood and is life-long, but early diagnosis and treatment can reduce the risk of adverse health complications. Dr Tye-Din said the newly developed testing strategy showed coeliac disease potentially affected at least one in 60 Australian women and one in 80 men. Previous estimates had the number of Australians with coeliac disease as no more than one in 100. Although this study is the first to reveal that more than half of Australians have genetic risk factors for developing coeliac disease, it is not yet known why the disease develops in only some people. Dr Tye-Din, who is also a gastroenterologist at The Royal Melbourne Hospital, said the findings were surprising and shed new light on the medical burden of coeliac disease in Australia. “It is concerning that a significant number of people in the community with coeliac disease have not been diagnosed,” he said. “Accurate and timely diagnosis is important for the health of patients with coeliac disease. Making a diagnosis based on a blood test alone or commencing a gluten-free diet without a confirmatory bowel biopsy is inappropriate and can impose an unnecessary and lifelong treatment.