What is celiac disease? |

Risk Factors

Individuals whose family members have celiac disease are at risk for the illness. Individuals also are at risk if they have a history of another autoimmune disease, such as type 1 diabetes, autoimmune thyroid disease, lupus, dermatitis herpetiformis (a skin condition associated with celiac disease), and rheumatoid arthritis.

Etiology and Genetics

Celiac disease is a complex disorder that is determined by an interaction between both genetic and environmental components. According to a 2012 Journal of Biomedical Sciencearticle by F. Megiorni and A. Pizzuti, 90 to 95 percent of affected individuals have at least one allele heterodimer (combination) of two closely linked predisposing genes found at the major histocompatibility locus located on the short arm of chromosome 6 (at position 6p21.32). These alleles, known as HLA-DQA1 and HLA-DQB1, most commonly form the heterodimers DQ2 and DQ8. The HLA alleles are necessary but not sufficient to predispose the development of celiac disease, since some unaffected individuals also carry one or both of them.

Additionally, there are several other regions in the genome that are unlinked to the HLA region and that may contain genes for celiac disease susceptibility (at positions 1q31, 2q11, 2q33, 3q21, 3q25, 3q28, 4q27, 5q31, 12q24, 15q11, and 19p13.1). Each of these has a relatively weak effect as compared with the HLA alleles, but they serve to complicate the inheritance patterns and make predictions of outcomes more unreliable.

Incidence of the disease in first-degree relatives of affected individuals is about 10 to 12 percent, and concordance rates for celiac disease in identical twins have been reported to be about 83 to 85 percent, according to Megiorni and Pizzuti. By contrast, the prevalence among the general US population was about 1 in 141 people in 2012, as reported by the National Institute of Diabetes and Digestive and Kidney Diseases.

The environmental factors that may serve to trigger the development of the disease are also not well understood, although a diet high in gluten is certainly a prerequisite. Other contributing environmental factors that have been reported include stress, pregnancy, traumatic injury, surgery, and systemic infections.

Symptoms

Symptoms vary and may start in childhood or adulthood. Children often have different symptoms from adults. Symptoms may not develop if a large section of the intestine is undamaged. Malnutrition may produce the first signs of the condition, which are often the most serious.

Signs and symptoms in children may include abdominal pain; nausea or lack of appetite; vomiting, in later stages of the disease; diarrhea; malodorous, bulky stools; irritability; and failure to thrive (in infants). Other signs and symptoms in children may include short stature, delayed puberty, anemia, pale skin, seizures, hepatitis, angular cheilitis (cracked sores in the corners of the mouth), and aphthous ulcers (shallow sores in the mucous membranes of the mouth).

Signs and symptoms in adults include bloating, gas, diarrhea, and a foul-smelling, light-colored, oily stool. Additional signs and symptoms are weight loss, a hearty or a poor appetite, fatigue, abdominal pain, bone pain, behavior changes, muscle cramps and joint pain, seizures, dizziness, skin rash, dental problems, missed menstrual periods, infertility, altered sensation in the limbs, anemia, and osteopenia.

Screening and Diagnosis

The doctor will ask about an individual’s symptoms and medical history and will conduct a physical exam. Symptoms of celiac disease are similar to those of other conditions. It may take a long time to get a diagnosis. Early diagnosis and treatment reduce the risk of complications.

Tests may include blood tests to detect the presence of gluten antibodies (produced by the immune system) and to look for evidence of malabsorption (anemia, vitamin and mineral deficiencies). Stool tests can check for evidence of malabsorption. Other tests include endoscopy, in which a thin, lighted tube is inserted down the throat to examine the intestine; biopsy, in which a small sample of tissue is removed during endoscopy to test for inflammation and tissue damage; and repeat biopsy, a biopsy performed several weeks after treatment begins to confirm the diagnosis.

Treatment and Therapy

A lifelong gluten-free diet is the only treatment for celiac disease; fortunately, it is very effective. Symptoms usually go away within days of starting the diet. Healing of the villi may take months or years. Additional intake of gluten can damage the intestine, even if the patient has no symptoms. Delayed growth and tooth discoloration may be permanent. Nutritional supplements, given through a vein, may be needed if the intestinal damage is significant and does not heal. Since gluten is added to many foods, the diet can be complicated and often frustrating. Some patients find support groups helpful.

Individuals with celiac disease must avoid all foods containing wheat, rye, or barley. This includes most bread, pasta, cereal, and processed foods. Special gluten-free breads and pastas are available; they are made with potato, rice, soy, or bean flour. Patients who are lactose intolerant before their small intestine heals need to avoid milk products. A dietitian can assist patients with meal planning.

Gluten is found in some unexpected foods and beverages; patients should carefully read all labels. Other foods with gluten include flavored coffee, beer, tuna in vegetable broth, packaged rice mixes, some frozen potatoes, creamed vegetables, commercially prepared vegetables, salads and salad dressings, pudding, some ice cream, and many other products. Ordering at restaurants can be especially challenging, since many foods on the menu may surprisingly contain gluten.

Patients with celiac disease should be tested for nutritional deficiencies. Bone density testing may also be needed. If vitamin or mineral deficiencies are found, the doctor may recommend taking supplements. Once the disease is under control with a gluten-free diet, however, this is often not necessary.

Prevention and Outcomes

There are no guidelines for preventing celiac disease because the cause is not understood. If celiac disease runs in an individual’s family, he or she should ask the doctor about a screening test. The earlier patients start the gluten-free diet, the less damage there will be to their intestines.

Bibliography

Bope, Edward T., and Rick D. Kellerman. Conn’s Current Therapy 2014. Philadelphia: Saunders, 2014. Print.

DiMarino, Anthony J., Jr. Sleisenger and Fordtran’s Gastrointestinal and Liver Disease: Review and Assessment. 9th ed. Philadelphia: Saunders, 2010. Print.

Domino, Frank J., Robert A. Baldor, Jeremy Golding, and Jill A. Grimes, eds. Griffith’s Five-Minute Clinical Consult, 2014. 22nd ed. Philadelphia: Lippincott, 2014. Print.

Goldman, Lee, and Andrew I. Schafer, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia: Saunders Elsevier, 2012. Print.

Green, Peter H. R., and Rory Jones. Celiac Disease: A Hidden Epidemic. Rev. ed. New York: Collins, 2010. Print.

Kliegman, Robert M., et al., eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia: Saunders, 2011. Print.

Megiorni, Francesca, and Antonio Pizzuti. "HLA-DQA1 and HLA-DQB1 in Celiac Disease Predisposition: Practical Implications of the HLA Molecular Typing." Journal of Biomedical Science 19.1 (2012): 88. Web. 24 July 2014.

Shepard, Jules E. Dowler. The First Year—Celiac Disease and Living Gluten-Free: An Essential Guide for the Newly Diagnosed. Cambridge: Da Capo, 2008. Print.