Celiac disease (CD) is a common immune-mediated enteropathy with a prevalence of approximately 1% within the U.S. and European populations. There is however a world-side disease distribution, including Mexico, South America, the Middle East, parts of India, and specific regions of Africa. While the classic and usually obvious consequences of the enteropathy are malabsorption with diarrhea, weight loss, and nutritional deficiencies, the difficulty in diagnosis is due in large part to the silent form of the disease which comprises the majority of patients. Overall mild clinical symptoms with nonspecific complaints such as fatigue, headaches, arthralgias are common and can delay diagnosis. A large, multi-center study in the United States showed an increased disease prevalence in high risk groups, including patients with autoimmune insulin-dependent diabetes mellitus, Sjogren's syndrome, osteoporosis, and first degree relatives of patients with CD; in addition to diarrhea, abdominal pain and constipation were among the most highly reported symptoms.  Because of the diagnostic difficulties inherent in this often mild or clinically silent presentation, identification of high risk groups for serological screening may decrease time to diagnosis and lessen the complications of untreated disease.
Several studies have recently demonstrated the cost-effectiveness of screening the IBS population for CD. Results from one recent study addressed the possibility of immunologically-based mechanisms following gluten exposure contributing to IBS symptoms that may represent a ‘celiac-like’ disorder. This study showed decreases in stool frequency and improvement in the gastrointestinal symptoms score among 60% of patients with diarrhea-predominant IBS and who carried the celiac disease associated HLA type (DQ2), but lacked fully developed celiac disease. 
Various autoimmune diseases have been historically associated with CD. [3, 4] These findings raise interesting questions as to whether abnormal immune responses at the level of the gut mucosa when exposed to environmental antigens, play a role in systemic autoimmune disease or if these associations reflect more an underlying, genetic predisposition. Proposed mechanisms of association include abnormal regulation of intestinal permeability and increased autoantibody production in the setting of chronic gut inflammation.
This review will focus on the autoimmune connective tissue diseases, endocrine, and dermatological conditions associated with CD, as well as the related gut inflammatory disorders of refractory celiac disease, autoimmune enteropathy, collagenous enteritis, and collagenous colitis.