PARK CITY, UTAH – Dr. John J. Zone first began to study gluten sensitivity in 1977, an interest that left some of his clinician colleagues wondering why.
“Everybody told me I was crazy – that this was extremely rare. So I always say I was gluten when gluten wasn’t cool,” Dr. Zone, professor and chairman of dermatology at the University of Utah, Salt Lake City, told attendees at the annual meeting of the Pacific Dermatologic Association.
Dr. John J. Zone
These days, it’s hard to shop in a food market without noticing all the gluten-free foods available, from pizza dough to beer. Many restaurants also serve gluten-free dishes. But is it hype, or is gluten sensitivity that common? Five percent of people in the United States “will say they are gluten sensitive,” he said. “In fact, 1% of Caucasians actually have celiac disease and 1% of Caucasians have gluten sensitivity that can be documented by challenge but don’t have celiac disease, while 3% have nothing.”
Gluten is a group of proteins contained in wheat, barley, and rye that is insoluble in water. Dr. Zone described celiac disease as a “spectrum of disease” characterized by inflammation of the small intestinal mucosa that occurs with the ingestion of gluten. The condition improves when gluten is removed from the diet. From a genetic standpoint, having a predisposition to express human leukocyte antigen-DQ2 or HLA-DQ8 is required for a diagnosis of celiac disease (CD). An estimated 20%-25% of whites “have that HLA background, but it is rare in Asians,” he said. “The receptors coded by HLA genes are essential for the processing of the gliadin antigen in CD.”
The hallmark for CD is a blood test for immunoglobulin A (IgA) anti-tissue transglutaminase antibodies, which are detectable in patients with untreated disease. “You should be able to get that test for $50 or $60 in any laboratory in the country,” Dr. Zone said. “It’s about 98% reliable. You also want to do a total serum IgA to rule out IgA-deficiency.”
CD clusters with other autoimmune disorders such as Addison’s disease, autoimmune thyroiditis, atrophic gastritis, systemic lupus erythematosus, rheumatoid arthritis, myasthenia gravis, and vitiligo. It’s also common in Down syndrome. “Many patients with histological inflammation have atypical intestinal symptoms or none at all,” he said. “Clinical studies have shown that only 15%-20% of CD patients identified by serology and confirmed by biopsy have classical symptoms of diarrhea and malabsorption.” The presenting symptom in patients with celiac disease may be limited to only aphthous stomatitis, eczema, alopecia areata, psoriasis, or diabetes, along with fatigue or anemia.
Researchers who analyzed the prevalence of CD in the United States estimated the risk to be 1:133 among individuals deemed not to be at risk, 1:56 in symptomatic patients, 1:39 in second-degree relatives, and 1:22 in first-degree relatives (Arch Intern Med. 2003;163[3]:286-92.). “We tested 2,100 people in Utah and found the prevalence among first-degree relatives was 1:12,” Dr. Zone said. “The point is that CD is common, not rare. It’s as common as psoriasis. It profoundly affects the immune system, which is the modulator of inflammatory skin disease.”
Dr. Zone reported having no financial disclosures.