Trait Document

Celiac disease (CD) is an autoimmune disorder (i.e., a condition in which the body attacks its own cells) that is caused by an abnormal immune response to the ingestion of gluten. Gluten is a protein found in the grains wheat, barley, and rye. When individuals with CD consume gluten, an abnormal immune response causes inflammation in the lining of the intestine. Over time, the continued inflammation leads to damage to the lining of the intestine and symptoms of CD. Individuals with CD may experience a wide variety of symptoms, both intestinal and extra-intestinal. Intestinal symptoms include abdominal pain and/or distension, weight loss, anorexia, diarrhea, and flatulence. Extra-intestinal symptoms can include chronic fatigue, epilepsy, osteoporosis/osteopenia, dermatitis herpetiformis (a skin rash) and/or infertility. Individuals with prominent intestinal symptoms are said to have classic CD, while those with prominent extra-intestinal symptoms are said to have nonclassic CD. Some individuals with CD may not have any symptoms; this is referred to as silent CD.

Although there are many factors that influence an individuals risk of developing CD, changes or variants in certain genes, such as variants in the HLA-DQA1 gene (e.g., HLA-DQ2 haplotype) and the HLA-DQB1 (e.g., HLA-DQ8 haplotype) gene, as well as many others, appear to be responsible for approximately 50% of the reasons for individuals developing CD. Approximately 30-35% of individuals in the general population in the United States have either the HLA-DQ2 or HLA-DQ8 CD-susceptibility haplotype, while only 2-5% of these allele carriers go on to develop CD. Virtually all individuals with CD have one of these two CD-associated alleles.

A combination of clinical assessment of symptoms, blood testing for celiac antibodies, biopsy of the small intestine by endoscopy, genetic testing, and clinical follow-up are used to make a diagnosis of CD. Findings suggestive of CD include: (1) intestinal and/or extra-intestinal symptoms; (2) high levels of CD antibodies present in the blood; (3) characteristic changes to the lining of the intestine on biopsy; (4) HLA-DQ2 haplotype and/or HLA-DQ8 haplotype; and (5) improvement of symptoms with a gluten-free diet. It is important that diagnostic workup be undertaken before initiation of a gluten-free diet because specific blood tests and intestinal biopsy results depend upon the presence of gluten in the diet.

In addition to genetic factors, having another autoimmune disorder (e.g., type 1 diabetes) is also a risk factor of CD. Additionally, compared to African Americans, European Americans are more likely to develop CD.

The treatment for CD is a strict life-long adherence to a gluten-free diet. A dietician experienced in treating individuals with CD should be involved to educate individuals with CD about common food items with hidden gluten, such as soy sauce, and non-food items, such as medications, postage stamp glue, and cosmetics. Complications of CD, including nutritional deficiencies and osteoporosis, can be treated in the standard manner.

An individuals response to the gluten-free diet is monitored by checking celiac antibody levels in the blood each year. Additional yearly surveillance may involve blood testing to screen for thyroid disorders and diabetes mellitus, which occur more frequently in individuals with CD. Bone mineral density, a non-invasive test similar to an X-ray, may also be done to rule out or monitor osteoporosis/osteopenia (low bone mineral density).

CD is a complex condition, which means that it is caused by a combination of many different factors. These factors can be genetic or non-genetic (such as environmental factors). Complex conditions are inherited in a multifactorial pattern. This means that the chance for an individual to develop CD is influenced by the number and type of genetic and non-genetic factors occur together to which an individual is exposed. In other words, no single gene, and no single environmental factor cause CD. However, not all of these genetic factors and environmental factors are known.

Studies suggest the risk for CD is 7-20% for siblings of an individual with CD and 5 to 10% for parents and children of an individual with CD. For siblings of an individual with CD that inherit the same CD-susceptibility allele (e.g., HLA-DQ2 and/or HLA-DQ8 haplotypes), the risk for CD could be as high as 40%.

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