Celiac disease occurs when the body reacts abnormally to gluten, a protein found in wheat, rye, barley, and possibly oats. When someone with celiac disease eats foods containing gluten, that person’s immune system causes an inflammatory response in the small intestine, which damages the tissues and results in an impaired ability to absorb nutrients from foods. The inflammation and malabsorption create various problems in many systems of the body. Since the body’s own immune system causes the damage, celiac disease is classified as an autoimmune disorder. This means that it is a disease characterized by abnormal functioning of the immune system that causes your immune system to produce antibodies against your own tissues. Each person with celiac disease is affected differently. When food containing gluten reaches the small intestine, the immune system begins to attack a substance called gliadin, which is found in the gluten eaten. The resulting inflammation causes damage to the delicate finger–like structures in the intestine, called villi, where food absorption actually takes place (2011). This damage is referred to as villus atrophy. The patient may experience a number of symptoms related to the inflammation and the chemicals it releases, and/or the lack of ability to absorb nutrients from food, which can cause malnutrition. When a person with celiac disease consumes gluten, the villi of the small intestine become damaged, resulting in nutrients passing through the digestive system without being absorbed. The person exhibits gastrointestinal distress and eventually malnutrition. In infancy, celiac disease can manifest as failure to thrive, diarrhea, abdominal distention, developmental delay, and in some infants, as severe malnutrition.
First-century Greek physician Aretaeus of Cappodocia created a medical chart of a modern gluten-intolerant patient. Aretaeus describes fatigue, bloating, flatulence, weakness, and diarrhea. In addition, he notes that not only does the disease cause failure of digestion, but there is failure to distribute even the partly digested product required for body growth. English pediatrician Samuel Gee picked up the ancient Greek physician's work in 1888, and described a specific case of coeliac affection in St. Bartholomew's Hospital Reports. Gee applied Aretaeus's observation that the condition affects body growth, noting that it especially affected children between one and five years old. Gee determined that regulating the diet could alleviate symptoms, but did not isolate gluten intolerance as the cause. In 1924 the American pediatrician Sydney Haas treated eight children with celiac disease with a diet based on bananas. In addition to requiring the patient to eat four to eight bananas each day, Haas recommended the elimination of sucrose as well as bread, crackers, potatoes, and cereal. Until the early 1950s, Haas's specific carbohydrate diet was the standard treatment for celiac disease, although the diet did not exclude all sources of gluten. Then, Dutch pediatrician Willem-Karel Dicke developed a hypothesis that wheat was the offending culprit in gluten intolerance when he observed previously ill children who improved while bread shortages occurred during World War II. By the early 1950s, physicians who prescribed a gluten-free diet for patients with symptoms of celiac disease noted marked improvement. In fact, "Advancements in genetic testing in the 1990s and the first decade of the 2000s helped to pinpoint two specific genes related to celiac disease: The HLA-DQA1 and HLA-DQB1 genes" (Food, 2011). Having one or both copies, however, does not automatically mean that a person will inevitably develop a gluten-intolerance-related condition. Environmental triggers appear to be a significant component in whether patients develop gluten intolerance and are a fertile area for ongoing research.
The exact cause of celiac disease is unknown. It can run in families and has a genetic basis, but the pattern of inheritance is complicated. The type of inheritance pattern that celiac disease follows is multifactorial. Researchers think that several factors must exist in order for the disease to occur. First, the patient must have a genetic predisposition to develop the disorder. Then, something in their environment acts as a stimulus to trigger their immune system, causing the disease to become active for the first time. For conditions with multifactorial inheritance, people without the genetic predisposition are less likely to develop the condition with exposure to the same triggers (2011). Or, they may require more exposure to the stimulus before developing the disease than someone with a genetic predisposition. This combination of genetic susceptibility and an outside agent leads to celiac disease.
As for the specific genes, the risk of developing celiac disease is increased by certain variants of the HLA-DQA1 and HLA-DQB1 genes. These genes provide instructions for making proteins that play a critical role in the immune system. The HLA-DQA1 and HLA-DQB1 genes belong to a family of genes called the HLA complex. The HLA complex helps the immune system distinguish the body's own proteins from proteins made by foreign invaders such as viruses and bacteria. The proteins produced from the HLA-DQA1 and HLA-DQB1 genes attach to each other to form a functional protein complex called an antigen-binding DQαβ heterodimer. This complex, which is present on the surface of certain immune system cells, attaches to peptides outside the cell. If the immune system recognizes the peptides as foreign such as viral or bacterial peptides, it triggers a response to attack the invading viruses or bacteria. This is the case when gluten enters the digestive system of the body.
The most commonly recognized symptoms of celiac disease relate to the improper absorption of food in the gastrointestinal system. The patient will have diarrhea and fatty, greasy, unusually foul-smelling stools. The patient may complain of excessive gas, distended abdomen, weight loss, and generalized weakness. A distinctive skin rash, called dermatitis herpetiformis, is present in approximately 10% of patients with celiac disease. Unrecognized and therefore untreated celiac disease may cause or contribute to a variety of other medical conditions. The decreased ability to digest, absorb, and utilize food properly may cause anemia from iron deficiency or easy bruising from a lack of vitamin K (2011). Poor mineral absorption may result in osteoporosis, commonly called brittle bones, which may lead to bone fractures. Vitamin D levels may be insufficient and bring about a softening of bones or osteomalacia, which produces pain and bony deformities. Defects in the tooth enamel, characteristic of celiac disease, may be recognized by dentists. Celiac disease may cause a failure to thrive in infants, or lack of proper growth in children and adolescents. People with celiac disease may also experience lactose intolerance as well. Whereas celiac disease remains the most severe of the disorders associated with gluten intolerance, in the latter half of the twentieth century new forms of gluten intolerance were identified. Gluten intolerance differs from a true food allergy in that the two conditions trigger different immune responses. Wheat allergies, for instance, trigger immunoglobulin antibodies, while for people with gluten intolerance, blood work identifies high levels of anti-tissue transglutaminase antibodies as a marker for diagnosis.
If celiac disease is suspected, a blood test can be ordered. This test looks for the antibodies to gluten that the immune system produces in celiac disease. Antibodies are chemicals produced by the immune system in response to substances that the body perceives to be threatening. Some experts advocate not just evaluating patients with symptoms, but using these blood studies as a screening test for high–risk individuals, such as those with relatives known to have the disorder. An abnormal result points towards celiac disease, but further tests are needed to confirm the diagnosis. Because celiac disease affects the ability of the body to absorb nutrients from food, several tests may be ordered to look for nutritional deficiencies. For example, doctors may order a test of iron levels in the blood because low levels of iron -anemia- may accompany celiac disease. Doctors may also order a test for fat in the stool, since celiac disease prevents the body from absorbing fat from food.
The only treatment for celiac disease is a gluten–free diet. This may be easy for the doctor to prescribe, but difficult for the patient to follow. For most people, adhering to this diet will stop symptoms and prevent damage to the intestines. Damaged villi can be functional again in three to six months. This diet must be followed for life. For people whose symptoms are cured by the gluten–free diet, this is further evidence that their diagnosis is correct. Gluten is present in any product that contains wheat, rye, barley, or oats. It helps make bread rise, and gives many foods a smooth, pleasing texture. In addition to the many obvious places gluten can be found in a normal diet, such as breads, cereals, and pasta, there are many hidden sources of gluten. These include ingredients added to foods to improve texture or enhance flavor and products used in food packaging. Gluten may even be present on surfaces used for food preparation or cooking.
Guidelines for a gluten-free diet have been developed by dietitians for several organizations associated with celiac disease. The gluten-free diet is used by individuals who are gluten-sensitive to prevent damage to their small intestines and to prevent serious complications such as gastrointestinal cancers, iron-deficiency anemia, and decreased bone mineral density. The diet includes food such as beans, corn, meat, etc that do not include gluten. In fact, "A gluten-free diet has been shown to greatly reduce the risk for cancer and overall mortality for individuals with symptomatic celiac disease" (The Gale Encyclopedia of Medicine, 2011). For many people with celiac disease, following a gluten-free diet will stop the symptoms of the disease and result in improved health, usually within several months, although for some individuals, recovery may take up to one year. Treating celiac disease with a gluten free diet is almost always completely effective. It should be noted that, "Gastrointestinal complaints and other symptoms are alleviated. Secondary complications, such as anemia and osteoporosis, resolve in almost all patients. People who have experienced lactose intolerance related to their celiac disease usually see those symptoms subside as well" (The Gale Encyclopedia of Genetic Disorders, 2010). Although there is no risk and much potential benefit to this treatment, it is clear that avoiding all foods containing gluten can be difficult. Experts emphasize the need for lifelong adherence to the gluten free diet to avoid the long–term complications of this disorder. It is pointed out that although the disease may have symptom–free periods if the diet is not followed, silent damage always continues to occur. Celiac disease cannot be outgrown or cured, according to medical authorities.
Hypothetically speaking, gene therapy could be used to cure celiac disease through the use of extracting the mutated gene and replacing it with a unmutated gene. Gene therapy is an experimental technique that uses genes to treat or prevent disease. This technique may allow doctors to treat a disorder by inserting a gene into a patient’s cells instead of using drugs or surgery. For celiac disease specifically, the mutated genes would be the HLA-DQA1 and HLA-DQB1 genes. These two genes create peptides/proteins which react abnormally to the protein gluten, which then result in the symptoms for celiac disease. Gene therapy is designed to introduce genetic material into cells to compensate for abnormal genes or to make a beneficial protein. If a mutated gene or genes cause a necessary protein to be faulty or missing, gene therapy may be able to introduce a normal copy of the gene to restore the function of the protein. Gene therapy, to be specific, utilizes vectors which are virus like carries that genetically engineered to deliver the gene. This would allow for the HLA-DQA1 and HLA-DQB1 genes to work properly, therefore allowing the patient to digest gluten filled foods without an involuntary reaction.