title: Predictors of clinical response to gluten-free diet in patients diagnosed with diarrhea-predominant irritable bowel syndrome.
abstract: OBJECTIVE
  Gluten sensitivity might cause abdominal symptoms in the absence of villous atrophy. We examined the prevalence of celiac disease-associated serum antibodies in diarrhea-dominant irritable bowel syndrome (d-IBS) patients and their efficacy in combination with HLA-DQ2 expression to predict the response to gluten-free diet.
  
  
  METHODS
  HLA-DQA1*0501/DQB1*0201 expression and celiac disease-associated IgA and IgG serum antibodies against gliadin and tissue-transglutaminase were measured in 145 patients with d-IBS, 74 patients with untreated and treated celiac disease, and 57 patients with active IBD. Follow-up antibody levels, stool frequency, and gastrointestinal symptom scores were determined in 41 d-IBS patients (26 women, 15 men; median age, 46 years, range, 30-67 years) who participated in a nonrandomized evaluation of 6 months of gluten-free diet.
  
  
  RESULTS
  Increased celiac disease-associated serum IgG, but not IgA, was found in the majority of patients with treated (55%) as in most patients with untreated celiac disease (97%). In d-IBS patients, celiac disease-associated serum IgG antibodies (37%) and HLA-DQ2 expression (39%) were more frequent than in IBD patients (18% and 23%, respectively). After 6 months of gluten-free diet, stool frequency and gastrointestinal symptom score returned to normal values in 60% of d-IBS patients who were positive and in 12% who were negative for HLA-DQ2 and celiac disease-associated serum IgG; both parameters combined yielded positive and negative predictive values of 56% (95% confidence interval, 30%-80%) and 88% (69%-97%), respectively.
  
  
  CONCLUSIONS
  Celiac disease-associated serum IgG and HLA-DQ2 expression can identify likely responders to gluten-free diet in d-IBS patients.
authors.affiliation: Medical Clinic A, Department of Gastroenterology, Endocrinology and Nutritrion, University Hospital Ernst Moritz Arndt Universität Greifswald, Greifswald, Germany. ulrich.wahnschaffe@uni-greifswald.de
authors.forename: Ulrich
authors.initials: U
authors.lastname: Wahnschaffe
authors.forename: Jörg-Dieter
authors.initials: JD
authors.lastname: Schulzke
authors.forename: Martin
authors.initials: M
authors.lastname: Zeitz
authors.forename: Reiner
authors.initials: R
authors.lastname: Ullrich
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology; D002446:Celiac Disease / Q000150:complications / Q000178:diet therapy / Q000276:immunology; D003967:Diarrhea / Q000175:diagnosis / Q000178:diet therapy* / Q000209:etiology; D018753:Diet, Protein-Restricted / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D019204:GTP-Binding Proteins; D015870:Gene Expression; D005903:Gliadin / Q000276:immunology; D005983:Glutens / Q000009:adverse effects*; D006683:HLA-DQ Antigens / Q000235:genetics; D059848:HLA-DQ alpha-Chains; D059866:HLA-DQ beta-Chains; D006801:Humans; D007070:Immunoglobulin A / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D043183:Irritable Bowel Syndrome / Q000150:complications / Q000175:diagnosis / Q000178:diet therapy*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D012189:Retrospective Studies; D011503:Transglutaminases / Q000276:immunology
chemical_list: D000888:Antibodies, Anti-Idiotypic; D006683:HLA-DQ Antigens; D059848:HLA-DQ alpha-Chains; D059866:HLA-DQ beta-Chains; C069050:HLA-DQA1 antigen; C069051:HLA-DQB1 antigen; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D005983:Glutens; D005903:Gliadin; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins