* Abbreviations: CD = : celiac disease • HLA = : human leukocyte antigen • EmA = : antiendomysium antibodies • TJ = : tight junction • TTG = : tissue transglutaminase Celiac disease (CD) is an autoimmune enteropathy triggered by the ingestion of gluten-containing grains (ie, wheat, barley, and rye) in susceptible individuals. Both in vivo challenges and in vitro immunologic studies support the possibility that oat (once considered toxic for CD patients) can be safely ingested.1 However, because of uncontrolled harvesting and milling procedures, a cross-contamination of oat with gluten is a concern. It is the gliadin fraction of wheat gluten, and similar alcohol-soluble proteins in other grains, that are the environmental factors responsible for the development of the intestinal damage. The disease is associated with human leukocyte antigen (HLA) alleles DQA1\*0501/DQB1\*0201, and in the continued presence of gluten the disease is self-perpetuating.2 The typical intestinal damage characterized by loss of absorptive villi and hyperplasia of the crypts completely resolves on elimination of gluten-containing grains from the patients' diet. CD represents a common cause of malabsorption in western countries with apparent geographic variation in incidence. In the second century AD, Aretaeus from Cappadocia described what is believed to be the first report of a gastrointestinal condition resembling CD.3 Approximately 1700 years later, the connection between the ingestion of certain cereals and the onset of gastrointestinal symptoms typical of CD was established.4For the past 18 centuries, CD has been perceived as a disease whose clinical presentation was quite uniform. The case identification was entirely based on the search for symptoms such as chronic diarrhea, abdominal distension, and weight loss (or poor weight gain) occurring in young children a few weeks/months after the introduction of solid food to their diet. Therefore, early epidemiologic studies targeted the pediatric population experiencing this typical clinical presentation of the disease. In the past 5 decades, a substantial number of epidemiologic studies have been conducted in Europe to establish the frequency of …