Celiac Disease: All In The Family

Aliases: celiac disease, coeliac disease, celiac sprue, non-tropical sprue, and gluten sensitive enteropathy

Being gluten free is in fashion, but while it’s optional for some, it’s obligatory for the many suffering from celiac disease (CD). CD is an autoimmune disorder that’s estimated to affect 1 out of every 100 people2. The actual count is unknown, because a staggering 85-90% of people with the condition are undiagnosed1. That means that in the US alone, 2.5 million people with CD are unaware that they have the disease2.

Although public awareness of CD has certainly increased recently (to the point where people are sick of hearing the phrase “gluten free”), improvement in diagnosis alone doesn’t explain the huge jump in case numbers. In fact, it doesn’t come close. Even controlling for better detection, the number of people with CD is growing rapidly; prevalence rates are doubling every 20 years. Environmental factors, like greater wheat consumption, are thought to have played a role in this astronomical leap in prevalence, but the importance and extent of their contribution remains unclear1.

While the environmental triggers and even the symptoms of this complex disease are difficult to disentangle (see below), its genetics have proved relatively straightforward. CD is the most common genetically-based food intolerance in the world, and it hinges on two genes. People with the HLA-DQ2 or DQ8 genes are at a greater risk for CD, these genes contribute about 40% of the disease risk. Its strong genetic links keep CD in the family; having an immediate family member with the disease gives you a 1 out of 10 chance of having it1.

celiac disease
Gluten free is the way to be.

Cause: Like most autoimmune diseases, CD results from a combination of genetic predisposition and environmental factors. Once the disease is active, it is expressed when the ill consume gluten, a protein found in several grains, including wheat, rye, and barley2. Several environmental factors increase the likelihood of developing CD, including early infections, infant gut microbiota, and the amount and timing of the first exposure to gluten1.

Consequence: When gluten is digested by someone with CD, their body misidentifies it as a pathogen and sets off an immune response that attacks the lining of the small intestine, damaging the villi. This causes inflammation and impairs nutrient absorption, which can lead to an array of about 300 possible symptoms, including abdominal bloating and pain, weight loss, fatigue, migraines, irritability, and depression2. Although it is a disease of the gut, gastrointestinal symptoms can be minor or even absent, while symptoms outside the digestive tract can be major1. And to heap injury upon injury, CD is also associated with a range of other conditions, including anemia, osteoporosis, infertility, epilepsy, Type I diabetes, multiple sclerosis, and intestinal cancers2. The older a person is when he or she is diagnosed, the greater his or her chance of developing another autoimmune disorder; one study found that people diagnosed with CD after age 20 had a 34% chance of developing another autoimmune disorder2.

Cure: Because of its ridiculous number of symptoms, definitively diagnosing CD is a tricky business. Typically, once the disease is suspected a blood test is used to look for celiac-specific antibodies and, if positive, damage to the intestinal lining is then assessed with a biopsy. The only treatment for celiac disease is avoidance: a strict gluten free diet1. Some ties bind for life.

References

  1. Guandalini, S. & A. Assiri. 2014. Celiac disease: a review. JAMA Pediatrics, 168: 272-278.
  1. What is Celiac Disease? Celiac Disease Foundation. Web. 9 June 2015.

Image source: Creative Commons, http://www.marksdailyapple.com/gluten-free-fad/#axzz3d6qrTOfc

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Suzi Claflin

I am a postdoctoral fellow studying chronic disease epidemiology.

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