Variability of anti-human transglutaminase testing in celiac disease across Mediterranean countries.

AIM: To verify the precision and accuracy of transglutaminase antibodies (TGA) assays across Mediterranean countries. METHODS: This study involved 8 referral centres for celiac disease (CD) in 7 Mediterranean countries. A central laboratory prepared 8 kits of 7 blinded and randomized serum samples, with a titrated amount of Human TGA IgA. Each sample was analysed three times on three different days, with each centre running a total of 21 tests. The results were included in a blindly coded report form, which was sent to the coordinator centre. The coordinator estimated the mean coefficient of Variation (CoVar = σ/µ), the mean accuracy (Accur = Vobserved - Vreal) and the mean percent variation (Var% = [(Vobserved - Vreal)/Vreal] × 100). RESULTS: The analysis showed that 79.17% of the mean variation fell between -25% and +25% of the expected value, with the accuracy and precision progressively increasing with higher titres of TGA. From values 1.25 times greater than the normal cut-off, the measurements were highly reliable. CONCLUSION: TGA estimation is a crucial step for the diagnosis of CD; given its accuracy and precision, clinicians could be confident in establishing a diagnosis.

Impact on parents of HLA-DQ2/DQ8 genotyping in healthy children from coeliac families.

Due to the association of coeliac disease and HLA-specificities DQ2 and DQ8, HLA-typing can be used for risk determination of the disease. This study was designed to evaluate the knowledge of parents from coeliac families regarding HLA-typing and the impact of HLA-typing on the perception of the health of their children. A structured questionnaire was sent to the Dutch, Spanish and German parents participating with their child in the European PreventCD study on disease prevention in high-risk families, addressing parents' understanding of and attitude towards HLA-typing, distress related to HLA-typing and perceived health and health-related quality of life of their children. Sixty-eight percent of parents of 515 children returned the questionnaires, with 85% of children being DQ2/DQ8 positive. The majority of all parents answered the questions on knowledge correctly. Forty-eight percent of parents of DQ2/DQ8-negative children thought their child could develop coeliac disease. More distress was reported by parents of DQ2/DQ8-positive children (P<0.001). All parents showed few regrets and would repeat HLA-typing in future children. Perceived health and health-related quality of life were similar. In conclusion, we can say that misinterpretation of DQ2/DQ8-negative results by parents is frequent. DQ2/DQ8-positive results do not affect perceived health and health-related quality of life of children but may cause temporary negative feelings among parents. Parents of coeliac families seem to support HLA-typing.

Randomized feeding intervention in infants at high risk for celiac disease.

BACKGROUND: A window of opportunity has been suggested for reducing the risk of celiac disease by introducing gluten to infants at 4 to 6 months of age. METHODS: We performed a multicenter, randomized, double-blind, placebo-controlled dietary-intervention study involving 944 children who were positive for HLA-DQ2 or HLA-DQ8 and had at least one first-degree relative with celiac disease. From 16 to 24 weeks of age, 475 participants received 100 mg of immunologically active gluten daily, and 469 received placebo. Anti-transglutaminase type 2 and antigliadin antibodies were periodically measured. The primary outcome was the frequency of biopsy-confirmed celiac disease at 3 years of age. RESULTS: Celiac disease was confirmed by means of biopsies in 77 children. To avoid underestimation of the frequency of celiac disease, 3 additional children who received a diagnosis of celiac disease according to the 2012 European Society for Pediatric Gastroenterology, Hepatology, and Nutrition diagnostic criteria (without having undergone biopsies) were included in the analyses (80 children; median age, 2.8 years; 59% were girls). The cumulative incidence of celiac disease among patients 3 years of age was 5.2% (95% confidence interval [CI], 3.6 to 6.8), with similar rates in the gluten group and the placebo group (5.9% [95% CI, 3.7 to 8.1] and 4.5% [95% CI, 2.5 to 6.5], respectively; hazard ratio in the gluten group, 1.23; 95% CI, 0.79 to 1.91). Rates of elevated levels of anti-transglutaminase type 2 and antigliadin antibodies were also similar in the two study groups (7.0% [95% CI, 4.7 to 9.4] in the gluten group and 5.7% [95% CI, 3.5 to 7.9] in the placebo group; hazard ratio, 1.14; 95% CI, 0.76 to 1.73). Breast-feeding, regardless of whether it was exclusive or whether it was ongoing during gluten introduction, did not significantly influence the development of celiac disease or the effect of the intervention. CONCLUSIONS: As compared with placebo, the introduction of small quantities of gluten at 16 to 24 weeks of age did not reduce the risk of celiac disease by 3 years of age in this group of high-risk children. (Funded by the European Commission and others; PreventCD Current Controlled Trials number, ISRCTN74582487.).

Antibodies to wheat high-molecular-weight glutenin subunits in patients with celiac disease.

BACKGROUND: Wheat gluten comprises gliadins and glutenins. The high-molecular-weight (HMW) glutenin subunits (GS)-1Dy10 are toxic for patients with celiac disease (CD). This study aimed to assess whether CD patients mount a serological response to HMW-GS-1Dy10. METHODS: Recombinant HMW-GS-1Dy10 was deamidated using human recombinant tissue transglutaminase. MALDI-TOF was performed to compare the level of deamidation of glutamine residues between material before and after treatment. Enzyme-linked immunosorbent assays were developed. Sera from patients with untreated CD and gastrointestinal disease controls were tested and receiver operator characteristics were used to calculate cutoffs. RESULTS: MALDI-TOF revealed a number of fragments matching known HMW-GS-1Dy10 sequences within both the deamidated and non-deamidated material. Evidence of deamidation of glutamine residues was found only within the human transglutaminase-treated material. Patients with untreated CD had significantly increased levels of serum antibodies to HMW-GS-1Dy10 compared to controls. Undeamidated HMW-GS-1Dy10 IgA antibodies had sensitivities and specificities of 72.5 and 78.26%, respectively. Deamidated HMW-GS-1Dy10 IgA antibodies had sensitivities and specificities of 76.8 and 65.2%. Undeamidated HMW-GS-1Dy10 IgG antibodies had sensitivities and specificities of 75.3 and 68.1%. Deamidated HMW-GS-1Dy10 IgG antibodies had sensitivities and specificities of 36.2 and 92.8%. CONCLUSION: Patients with untreated CD have raised antibody levels to HMW-GS-1Dy10, indicating the participation of these proteins in the adaptive immune response to gluten. Discrimination between CD patients and controls is not enhanced by deamidation of HMW-GS-1Dy10. Thus antibodies to these proteins are not useful markers for CD detection.

The prevalence of celiac disease in Europe: results of a centralized, international mass screening project.

INTRODUCTION: Although the prevalence of celiac disease (CD) has been extensively investigated in recent years, an accurate estimate of CD frequency in the European population is still lacking. The aims of this study were: 1) to establish accurately the prevalence of CD in a large sample of the European population (Finland, Germany, Italy, and UK), including both children and adults; and 2) to investigate whether the prevalence of CD significantly varies between different areas of the European continent. MATERIALS AND METHODS: Samples were drawn from the four populations. All 29,212 participants were tested for CD by tissue transglutaminase (tTG) antibody test. Positive and border-line findings were further tested for serum endomysial antibodies (EMA). All serological determinations were centrally performed. Small-bowel biopsies were recommended to autoantibody-positive individuals. Previously diagnosed cases were identified. RESULTS: The overall CD prevalence (previously diagnosed plus anti-tTG and EMA positives) was 1.0% (95% CI 0.9-1.1). In subjects aged 30-64 years CD prevalence was 2.4% in Finland (2.0-2.8), 0.3% in Germany (0.1-0.4), and 0.7% in Italy (0.4-1.0). Sixty-eight percent of antibody-positive individuals showed small-bowel mucosal changes typical for CD (Marsh II/III lesion). CONCLUSIONS: CD is common in Europe. CD prevalence shows large unexplained differences in adult age across different European countries.

Mortality excess in individuals with elevated IgA anti-transglutaminase antibodies: the KORA/MONICA Augsburg cohort study 1989-1998.

OBJECTIVES: Immunoglobulin A (IgA) autoantibodies to tissue transglutaminase (tTG) are commonly used for screening and diagnosing of celiac disease. We examined the hypothesis that elevated IgA anti-tTG antibodies were associated with higher all-cause mortality risk. METHODS: The cohort, 2333 men and 2300 women, was based on the follow-up of participants of a representative population-based survey in Southern Germany (KORA/MONICA Augsburg project) conducted in 1989-1990. The endpoint for the vital status with cause of death was the year 1998. The sera drawn at baseline and stored at -80 degrees C, were recently screened with an IgA enzyme-linked immunosorbent assay (ELISA) using human recombinant tTG. Age-standardized mortality rates and age-adjusted hazard ratios were calculated. RESULTS: From the 4633 sera analyzed, 63 had an IgA anti-tTG concentration>or=7 AU/ml. Of these 63 individuals, 15 died between 1989 and 1998. The age-adjusted hazard ratio (HRa) of all-cause mortality was 1.86 (95% CI: 1.01-3.41) and 3.92 (95% CI: 1.44-10.71) for men and women, respectively. The excess of cancer mortality was even higher with an HR(a) of 2.47 (95% CI: 0.89-6.83) in men and of 6.65 (95% CI: 2.04-21.63) in women. CONCLUSIONS: Individuals with elevated IgA anti-tTG antibodies had a highly increased mortality risk, particularly due to cancer. New studies are necessary to clarify if this increased risk is due to undiagnosed celiac disease or/and if this elevated IgA anti-tTG antibodies level is a marker of serious diseases like cancer, chronic liver disease or end-stage heart failure.

Usefulness of the organ culture system in the in vitro diagnosis of coeliac disease: a multicentre study.

OBJECTIVE: Diagnosis of coeliac disease is based on the presence of villous atrophy which recovers following a gluten-free diet. The presence of circulating antiendomysial antibodies as well as their disappearance after a gluten-free diet supports the diagnosis. It has also been demonstrated that antiendomysial antibodies are detectable in supernatants of cultured intestinal biopsies from patients with coeliac disease. The objective of this study was to compare the histology and antiendomysial antibodies in culture supernatants of intestinal biopsies to validate the in vitro organ culture system as a future diagnostic tool for coeliac disease. MATERIAL AND METHODS: Seventy-five antiendomysial serum-positive patients on a gluten-containing diet were evaluated. Patients underwent endoscopy with 5 biopsy fragments: 3 for histology, 1 cultured with and the other without gliadin-peptide activator. Antiendomysial antibodies were evaluated in all culture supernatants. RESULTS: Sixty-eight patients had evidence of villous atrophy, while 73 out of 75 were positive to the organ culture system. The agreement rate between organ culture and histology results was 94%. CONCLUSIONS: As all the centres participating in the study obtained good agreement between organ culture and histology results, the new system could be considered a reliable tool for the diagnosis of coeliac disease. Nevertheless, it is possible to highlight cases with an organ culture-positive and -negative histology. This feature could be of considerable interest because, as the sensitivity of organ culture seems to be greater than the initial histology, the new system might be useful in uncertain cases where the risk of missing the diagnosis of coeliac disease is high.