ESPGHAN Position Paper on Management and Follow-up of Children and Adolescents With Celiac Disease.

OBJECTIVES: To gather the current evidence and to offer recommendations for follow-up and management. METHODS: The Special Interest Group on Celiac Diseases of the European Society of Paediatric Gastroenterology Hepatology and Nutrition formulated ten questions considered to be essential for follow-up care. A literature search (January 2010-March 2020) was performed in PubMed or Medline. Relevant publications were identified and potentially eligible studies were assessed. Statements and recommendations were developed and discussed by all coauthors. Recommendations were voted upon: joint agreement was set as at least 85%. RESULTS: Publications (n = 2775) were identified and 164 were included. Using evidence or expert opinion, 37 recommendations were formulated on: The need to perform follow-up, its frequency and what should be assessed, how to assess adherence to the gluten-free diet, when to expect catch-up growth, how to treat anemia, how to approach persistent high serum levels of antibodies against tissue-transglutaminase, the indication to perform biopsies, assessment of quality of life, management of children with unclear diagnosis for which a gluten-challenge is indicated, children with associated type 1 diabetes or IgA deficiency, cases of potential celiac disease, which professionals should perform follow-up, how to improve the communication to patients and their parents/caregivers and transition from pediatric to adult health care. CONCLUSIONS: We offer recommendations to improve follow-up of children and adolescents with celiac disease and highlight gaps that should be investigated to further improve management.

Association in Clinical Practice Between Gluten Intake and Gluten Immunogenic Peptides in Celiac Children.

Background and Aims: The dietary compliance and its assessment in celiac disease (CD) patients on a strict gluten-free diet (GFD) remain a challenge. Two relatively new, validated methods have been proposed to detect occasional gluten ingestion: standardized dietary questionnaire and determination of urinary gluten immunogenic peptides (GIPs). Our aim was to prospectively assess dietary compliance via these methods and compare their results with those of tissue transglutaminase antibodies (tTGA). Methods: This was a prospective single-center study. Consecutive CD patients (aged 1-18 years) on a GFD scheduled for regular consultation between March and August 2019 were invited. In addition to standard care, a completed dietary questionnaire and urine sample for GIP were collected. Pearson's chi-square test, Fisher's exact test, and Mann-Whitney U test were performed. Results: Of the 156 eligible children, 110 provided informed consent. Completed dietary questionnaire, GIP, and tTGA results were available from 86 children (median age 12.8 years, median GFD duration 30 months, 65% female). Adherence to the GFD evaluated by GIP, dietary questionnaire, and anti-tTGA was 94.2%, 75.6% and 94.2%, respectively. No association was found between the tTGA results and the detection of GIP, as well as between the tTGA results and the dietary questionnaires scores (P = .5 and .312, respectively). The participants perceived both the questionnaire and the measurement of GIP as reassuring with regard to correct implementation of the GFD. Conclusion: All the 3 methods have limitations to monitor dietary compliance. The comparison of their performance shows that the best single method is the use of the validated dietary questionnaire, which should therefore be implemented in the regular care for children with CD. The most effective combination of dietary questionnaire and urinary GIP determination should be used in specific clinical situations.

Growth rate of coeliac children is compromised before the onset of the disease.

INTRODUCTION: Growth impairment has often been described in children who develop coeliac disease (CD). Based on data from the multicentre, longitudinal PreventCD study, we analysed the growth patterns of infants at genetic risk of CD, comparing those who developed CD by 6 years of age (CD 'cases', 113 infants) versus those who did not develop CD by 6 years (no CD 'controls', 831 infants). METHODS: Weight and length/height were measured using a longitudinal protocol. Raw measurements were standardised, computing z-scores for length/height and weight; a linear mixed model was fitted to the data in order to compare the rate of growth in the two cohorts. RESULTS: Neither cases nor controls had significant growth failure. However, when the mean z-scores for weight and height were analysed, there was a difference between the two groups starting at fourth month of life. When the growth pattern in the first year was analysed longitudinally using mixed models, it emerged that children who develop CD had a significantly lower growth rate in weight z-score (-0.028/month; 95% CI -0.038 to -0.017; p<0.001) and in length/height z-score (-0.018/month; 95% CI -0.031 to -0.005; p=0.008) than those who do not develop CD. When the whole follow-up period was analysed (0-6 years), differences between groups in both weight and length/height z-scores were confirmed. CONCLUSION: The growth of children at risk of CD rarely fell below 'clinical standards'. However, growth rate was significantly lower in cases than in controls. Our data suggest that peculiar pathways of growth are present in children who develop CD, long before any clinical or serological signs of the disease appear.

European Society Paediatric Gastroenterology, Hepatology and Nutrition Guidelines for Diagnosing Coeliac Disease 2020.

OBJECTIVES: The ESPGHAN 2012 coeliac disease (CD) diagnostic guidelines aimed to guide physicians in accurately diagnosing CD and permit omission of duodenal biopsies in selected cases. Here, an updated and expanded evidence-based guideline is presented. METHODS: Literature databases and other sources of information were searched for studies that could inform on 10 formulated questions on symptoms, serology, HLA genetics, and histopathology. Eligible articles were assessed using QUADAS2. GRADE provided a basis for statements and recommendations. RESULTS: Various symptoms are suggested for case finding, with limited contribution to diagnostic accuracy. If CD is suspected, measurement of total serum IgA and IgA-antibodies against transglutaminase 2 (TGA-IgA) is superior to other combinations. We recommend against deamidated gliadin peptide antibodies (DGP-IgG/IgA) for initial testing. Only if total IgA is low/undetectable, an IgG-based test is indicated. Patients with positive results should be referred to a paediatric gastroenterologist/specialist. If TGA-IgA is ≥10 times the upper limit of normal (10× ULN) and the family agrees, the no-biopsy diagnosis may be applied, provided endomysial antibodies (EMA-IgA) will test positive in a second blood sample. HLA DQ2-/DQ8 determination and symptoms are not obligatory criteria. In children with positive TGA-IgA <10× ULN at least 4 biopsies from the distal duodenum and at least 1 from the bulb should be taken. Discordant results between TGA-IgA and histopathology may require re-evaluation of biopsies. Patients with no/mild histological changes (Marsh 0/I) but confirmed autoimmunity (TGA-IgA/EMA-IgA+) should be followed closely. CONCLUSIONS: CD diagnosis can be accurately established with or without duodenal biopsies if given recommendations are followed.

Variation and Interdependencies of Human Milk Macronutrients, Fatty Acids, Adiponectin, Insulin, and IGF-II in the European PreventCD Cohort.

Human milk composition is variable. The identification of influencing factors and interdependencies of components may help to understand the physiology of lactation. In this study, we analyzed linear trends in human milk composition over time, the variation across different European countries and the influence of maternal celiac disease. Within a multicenter European study exploring potential prevention of celiac disease in a high-risk population (PreventCD), 569 human milk samples were donated by women from five European countries between 16 and 163 days postpartum. Some 202 mothers provided two samples at different time points. Protein, carbohydrates, fat and fatty acids, insulin, adiponectin, and insulin-like growth factor II (IGF-II) were analyzed. Milk protein and n-6 long chain polyunsaturated fatty acids decreased during the first three months of lactation. Fatty acid composition was significantly influenced by the country of residence. IGF-II and adiponectin concentrations correlated with protein content (r = 0.24 and r = 0.35), and IGF-II also correlated with fat content (r = 0.36), suggesting a possible regulatory role of IGF in milk macronutrient synthesis. Regarding the impact of celiac disease, only the level in palmitic acid was influenced by this disease, suggesting that breastfeeding by celiac disease mothers should not be discouraged.

Ten years of follow-up of the Spanish cohort of the European PreventCD study: the lessons learned.

AIM: to evaluate the influence of gluten consumption on celiac disease development and to describe its natural history in the Spanish cohort of the European PreventCD study. METHODS: prospective multi-center double blind study of 225 children that were followed up from birth. All cases were HLA-DQ2/HLA-DQ8 positive with a 1st degree relative with celiac disease and were followed up in three centers from Madrid, Reus and Valencia. Gluten intake was determined between four and ten months according to the protocol. Gluten intake was ad libitum between eleven and 36 months and was prospectively quantified by means of dietary records. Clinical visits and specific antibody analysis for celiac disease were performed periodically. RESULTS: twenty-six cases were diagnosed, all had a positive biopsy and serology; 21 had gastrointestinal symptoms and five were asymptomatic. In addition, 2,565 food records were analyzed and statistically significant differences (p < 0.001) were found with regard to gluten consumption among the three centers, although not between celiac and non-celiac children (p = 0.025). The HLA-DQ2.5/DQ2.5 and DQ2.5/DQ2.2 genotypes had a relative risk of 4.7 (95% CI: 0.80-27.55; p = 0.08), which was higher than for the rest of genotypes. Female gender also had a relative risk that was five times higher than that for males. CONCLUSIONS: the amount of gluten intake between 11 and 36 months or the duration of breast feeding were not risk factors for the development of CD in the Spanish population. The HLA genotype and gender were the most relevant associated factors. In this at-risk group, the disease presented before two years of age in the majority of the cases with a weak clinical expression.

Anti-gliadin antibodies in breast milk from celiac mothers on a gluten-free diet.

PURPOSE: To analyze the presence of total IgA and anti-gliadin antibodies (AGA) in BM from CD mothers who follow a gluten-free diet (GFD) and from mothers on a normal gluten-containing diet (ND). METHODS: 218 samples of mature milk were obtained at different months of lactation (1-6) from 83 mothers (2 or more samples per mother) from Italy (Naples), The Netherlands (Leiden) and Spain (Madrid, Valencia and Reus): 42 CD mothers on GFD for more than 2 years and 41 non-CD mothers on a ND. Whey samples were analyzed for AGA-IgA by an indirect homemade ELISA and for total IgA (g/L) by a commercial ELISA kit. RESULTS: AGA-IgA was detected in BM, both in mothers on a GFD and mothers on a ND. AGA-IgA levels in both groups of mothers, CD and non-CD, show the same trend towards decreasing slightly along the months of lactation (p = 0.91). A different trend is observed for total IgA levels, decreasing markedly in CD mothers from the first month of lactation onwards but remaining stable in non-CD mothers (p = 0.048). A statistically significant association was found between the means of total IgA and AGA-IgA (p < 0.001). CONCLUSION: AGA-IgA is present in BM from mothers on a ND as well as in BM from mothers who had been on a GFD for years. This reflects the existence of a long-lasting immunological memory independent of the mother's diet. If the presence of these antibodies has any role in promoting the acquisition of gluten tolerance in the infant, our study shows that children of CD mothers would be on equal conditions as children of non-CD mothers.

Accuracy in Diagnosis of Celiac Disease Without Biopsies in Clinical Practice.

BACKGROUND & AIMS: The guidelines of the European Society of Pediatric Gastroenterology, Hepatology, and Nutrition allow for diagnosis of celiac disease without biopsies in children with symptoms and levels of immunoglobulin A against tissue-transglutaminase (TGA-IgA) 10-fold or more the upper limit of normal (ULN), confirmed by detection of endomysium antibodies (EMA) and positivity for HLA-DQ2/DQ8. We performed a large, international prospective study to validate this approach. METHODS: We collected data from consecutive pediatric patients (18 years or younger) on a gluten-containing diet who tested positive for TGA-IgA from November 2011 through May 2014, seen at 33 pediatric gastroenterology units in 21 countries. Local centers recorded symptoms; measurements of total IgA, TGA, and EMA; and histopathology findings from duodenal biopsies. Children were considered to have malabsorption if they had chronic diarrhea, weight loss (or insufficient gain), growth failure, or anemia. We directly compared central findings from 16 antibody tests (8 for TGA-IgA, 1 for TGA-IgG, 6 for IgG against deamidated gliadin peptides, and 1 for EMA, from 5 different manufacturers), 2 HLA-DQ2/DQ8 tests from 2 manufacturers, and histopathology findings from the reference pathologist. Final diagnoses were based on local and central results. If all local and central results were concordant for celiac disease, cases were classified as proven celiac disease. Patients with only a low level of TGA-IgA (threefold or less the ULN) but no other results indicating celiac disease were classified as no celiac disease. Central histo-morphometry analyses were performed on all other biopsies and cases were carefully reviewed in a blinded manner. Inconclusive cases were regarded as not having celiac disease for calculation of diagnostic accuracy. The primary aim was to determine whether the nonbiopsy approach identifies children with celiac disease with a positive predictive value (PPV) above 99% in clinical practice. Secondary aims included comparing performance of different serological tests and to determine whether the suggested criteria can be simplified. RESULTS: Of 803 children recruited for the study, 96 were excluded due to incomplete data, low level of IgA, or poor-quality biopsies. In the remaining 707 children (65.1% girls; median age, 6.2 years), 645 were diagnosed with celiac disease, 46 were found not to have celiac disease, and 16 had inconclusive results. Findings from local laboratories of TGA-IgA 10-fold or more the ULN, a positive result from the test for EMA, and any symptom identified children with celiac disease (n = 399) with a PPV of 99.75 (95% confidence interval [CI], 98.61-99.99); the PPV was 100.00 (95% CI, 98.68-100.00) when only malabsorption symptoms were used instead of any symptom (n = 278). Inclusion of HLA analyses did not increase accuracy. Findings from central laboratories differed greatly for patients with lower levels of antibodies, but when levels of TGA-IgA were 10-fold or more the ULN, PPVs ranged from 99.63 (95% CI, 98.67-99.96) to 100.00 (95% CI, 99.23-100.00). CONCLUSIONS: Children can be accurately diagnosed with celiac disease without biopsy analysis. Diagnosis based on level of TGA-IgA 10-fold or more the ULN, a positive result from the EMA tests in a second blood sample, and the presence of at least 1 symptom could avoid risks and costs of endoscopy for more than half the children with celiac disease worldwide. HLA analysis is not required for accurate diagnosis. Clinical Trial Registration no: DRKS00003555.

The role of gluten consumption at an early age in celiac disease development: a further analysis of the prospective PreventCD cohort study.

Background: We previously found that the introduction of small quantities of gluten at 4-6 mo of age did not reduce the risk of celiac disease (CD) in a group of high-risk children. However, the consumption of high amounts of gluten early in life has been suggested to increase CD risk.Objective: The aim of this study was to evaluate this hypothesis by using data from the previous study of the PreventCD trial (www.preventcd.com).Design: Gluten intake was prospectively quantified by using specific food records between 11 and 36 mo of age in 715 children positive for the human leukocyte antigen (HLA)-DQ2 and/or HLA-DQ8 from 5 European countries. According to the PreventCD protocol, infants received 100 mg immunologically active gluten/d or placebo from 4 to 6 mo of age, with a stepwise and fixed gluten increase until age 10 mo and unrestricted intake thereafter. The primary outcome of the present study was the impact of the amount of gluten consumed from age 10 mo onward on CD development.Results: Mean daily gluten intakes from 10 mo onward were significantly different between countries for children at all ages (P < 0.001) but not between children who developed CD and those who did not within the same country (P > 0.05). The variables country, sex, intervention group, and gluten consumption pattern did not show significant associations with CD development risk (HRs not significant). In addition, the interaction between HLA risk group and gluten consumption pattern showed no significant risk on CD development, except for the DQ2.2/DQ7 haplotype (HR: 5.81; 95% CI: 1.18, 28.74; P = 0.031).Conclusions: Gluten consumption patterns as well as the amount of gluten consumed at 11-36 mo of age do not influence CD development for most related HLA genotypes in children with a genetic risk. This study reports the gluten consumption pattern in children at risk of CD from different European countries. This trial was registered at www.controlled-trials.com as ISRCTN74582487.

Complementary Serologic Investigations in Children with Celiac Disease Is Unnecessary during Follow-Up.

OBJECTIVES: To determine the frequency of nutritional deficiencies and thyroid dysfunction in children with celiac disease (CD) and during follow-up after initiation of a gluten-free diet. Laboratory investigations of hemoglobin, ferritin, calcium, folate, vitamin B12, vitamin D, and thyroid function are regularly ordered in children with CD despite sufficient evidence for these. STUDY DESIGN: Between 2009 and 2014, test results of hemoglobin, ferritin, folate, vitamin B12, calcium, vitamin D (25[OH]D), free thyroxin, and thyroid stimulating hormone of children with CD regularly seen at the Leiden University Medical Center were investigated. Laboratory reference ranges were used to define abnormal results. Pearson χ(2) test for trend, unpaired t test, and 1-way ANOVA were used for statistical analysis. RESULTS: Of the 182 children evaluated, 119 were newly diagnosed. On average, 17% of results per year were missing because of incomplete blood investigations. Iron deficiency (28%) and iron deficiency anemia (9%) were found at the time of diagnosis of CD. Folate (14%), vitamin B12 (1%), and vitamin D deficiencies (27%) were also seen. No hypocalcemia or thyroid dysfunction was found. At follow-up, iron deficiency, iron deficiency anemia, and folate and vitamin D deficiency were observed in 8%, 2%, 3%, and 25% of patients, respectively. Vitamin B12 deficiency, hypocalcemia, and thyroid disease were not found. CONCLUSIONS: Complementary blood investigations are relevant at the time of diagnosis of CD but have little diagnostic yield during follow-up visits once the patient is placed on a gluten-free diet. Thus, we recommend that these variables only be assessed on indication, such as fatigue or abnormal growth.

The PreventCD Study design: towards new strategies for the prevention of coeliac disease.

BACKGROUND: PreventCD (www.preventcd.com) is a European multicentre study, which studies the influence of infant nutrition, and that of genetic, immunologic and environmental factors, on the risk of developing coeliac disease (CD). The hypothesis is that it is possible to induce tolerance to gluten by introducing small quantities of gluten to infants, preferably while they are still being breast-fed, and that this might also reduce the risk for related autoimmune disorders. AIM: To describe the design of this ongoing European CD research project. METHODS: PreventCD encompasses two study designs and two study populations: (i) a European multicentre study: a prospective, double-blind, randomized dietary-intervention study among infants from families with high risk of CD, and (ii) a Swedish population-based CD screening study among 12-year-olds from the general population, divided into two birth cohorts that differ with respect to infant feeding practices. DISCUSSION: PreventCD is expected to elucidate some of the genetic and immunological mechanisms involved in the process of immune intolerance.

Long-term health and quality-of-life consequences of mass screening for childhood celiac disease: a 10-year follow-up study.

OBJECTIVE: Mass screening for celiac disease is controversial. The objective of this study was to determine whether detection of childhood celiac disease by mass screening improves long-term health status and health-related quality of life. METHODS: We conducted a prospective 10-year follow-up study of 32 children who were aged 2 to 4 years, had celiac disease identified by mass screening, and had a gluten-free diet (19) or a normal gluten-containing diet (13). The follow-up included assessments of general health status, celiac disease-associated symptoms, celiac disease-associated serum antibodies, and health-related quality of life. RESULTS: Ten years after mass screening, 81% of the children were adhering to a gluten-free diet. The health status improved in 66% of the treated children: in 41% by early treatment and in 25% by prevention of the gluten-dependent symptoms that they developed after diagnosis. For 19% of the children, treatment after screening would not have improved their health status, because they had no symptoms at screening and have remained symptom-free while consuming gluten. The health-related quality of life of the children with symptoms improved significantly after 1 year of gluten-free diet. Ten years after screening, the health-related quality of life of the children with celiac disease was similar to that of the reference population. CONCLUSION: Identification by mass screening led 10 years later to health improvement in 66% of children without deterioration of generic health-related quality of life. There is a good compliance after mass screening. In a research setting, delaying treatment for children without symptoms seems to be an option after a positive screening test. Long-term follow-up studies are needed to assess possible long-term complications in untreated, nonsymptomatic celiac disease.

Dietary compliance and health-related quality of life in patients with coeliac disease.

BACKGROUND AND OBJECTIVE: Coeliac disease is treated with a lifelong gluten-free diet (GFD). The aim of our study was to investigate whether the dietary (nondietary) compliance is associated with health-related quality of life (HRQoL) of coeliac patients. METHODS: Patients from our hospital, known with coeliac disease for more than 10 years, were invited to participate in a study on possible gluten tolerance. HRQoL was assessed by the Short Form-36 health survey, symptoms by the Gastrointestinal Symptom Rating Scale and dietary compliance by a food frequency questionnaire. HRQoL of coeliac patients was compared with that of the general population. RESULTS: Fifty-three biopsy-confirmed coeliac patients were divided into three groups according to gluten consumption: GFD (n = 33), gluten transgression (<10 g gluten/day; n = 8) and normal gluten-containing diet (>10 g gluten/day; n = 12). Compared with the general population, coeliac patients scored significantly worse on general health perception but significantly better on bodily pain and limitations due to physical problems. The results of the Gastrointestinal Symptom Rating Scale and the Short Form-36 health survey were similar in all three dietary groups. CONCLUSION: Although adhering to the GFD is strictly important to prevent future complications, patients who stop following GFD do exist and patients with partial or nonadherence report similar HRQoL compared with patients with strict adherence in this group of adult coeliac patients.

Gluten tolerance in adult patients with celiac disease 20 years after diagnosis?

BACKGROUND AND OBJECTIVE: Celiac disease (CD) is believed to be a permanent intolerance to gluten. A number of patients, however, discontinue the gluten-free diet (GFD) without developing symptoms or signs. The aim of our study was to investigate whether CD patients are capable of developing tolerance to gluten. METHODS: All 77 adult patients from our hospital known to have biopsy-proven CD for more than 10 years were invited to participate. We investigated symptoms, gluten consumption, antibodies for CD and other autoimmunity, human leukocyte antigen (HLA)-typing, bone mineral density, and performed small bowel biopsies. Tolerance was defined as no immunological or histological signs of CD while consuming gluten. RESULTS: Sixty-six patients accepted participation, but after review of the diagnostic biopsies 53 were found to have true CD. Twenty-three percent of patients had a gluten-containing diet, 15% admitted gluten transgression and 62% followed the GFD. Patients on a GFD had significantly more osteoporosis. Normal small bowel mucosa was found in four of eight on gluten-containing diet and in four of four with gluten transgression. Two patients were considered to have developed tolerance to gluten. One of them was HLA-DQ2/DQ8 negative. CONCLUSION: Development of tolerance to gluten seems possible in some patients with CD. Further follow-up will show whether this tolerance is permanent or only a long-term return to latency. This feature may be associated with genetic characteristics, especially with HLA genotypes that differ from DQ2 or DQ8. More insight into the mechanisms of the development of gluten tolerance may help to distinguish those CD patients that might not require life-long GFD.

The SPINK gene family and celiac disease susceptibility.

The gene family of serine protease inhibitors of the Kazal type (SPINK) are functional and positional candidate genes for celiac disease (CD). Our aim was to assess the gut mucosal gene expression and genetic association of SPINK1, -2, -4, and -5 in the Dutch CD population. Gene expression was determined for all four SPINK genes by quantitative reverse-transcription polymerase chain reaction in duodenal biopsy samples from untreated (n=15) and diet-treated patients (n=31) and controls (n=16). Genetic association of the four SPINK genes was tested within a total of 18 haplotype tagging SNPs, one coding SNP, 310 patients, and 180 controls. The SPINK4 study cohort was further expanded to include 479 CD cases and 540 controls. SPINK4 DNA sequence analysis was performed on six members of a multigeneration CD family to detect possible point mutations or deletions. SPINK4 showed differential gene expression, which was at its highest in untreated patients and dropped sharply upon commencement of a gluten-free diet. Genetic association tests for all four SPINK genes were negative, including SPINK4 in the extended case/control cohort. No SPINK4 mutations or deletions were observed in the multigeneration CD family with linkage to chromosome 9p21-13 nor was the coding SNP disease-specific. SPINK4 exhibits CD pathology-related differential gene expression, likely derived from altered goblet cell activity. All of the four SPINK genes tested do not contribute to the genetic risk for CD in the Dutch population.

The downstream modulator of interferon-gamma, STAT1 is not genetically associated to the Dutch coeliac disease population.

Coeliac disease (CD) is a complex genetic disorder. Its etiology is owing to multiple genes and environmental factors, such as gluten. The first event in the pathogenesis of CD after the ingestion of gluten is the activation of a Th1 immune response that leads to villous atrophy. Although this immune response seems crucial to the disease's development, only the HLA-DQ2/DQ8 genes have been identified as causative immune genes related to CD. Recently, the activation of the transcription factor STAT1 and changes in its expression levels have confirmed the participation of the Janus kinase-signal transducer and activator of transcription pathway in CD. Furthermore, as the STAT-1 gene is a positional candidate located in the CELIAC3 locus on chromosome 2, we speculate that alterations in this gene could be primarily responsible for the aberrant immune response that characterizes CD. Based on this functional and genetic evidence, we investigated the primary contribution of STAT-1 to CD. We performed a comprehensive genetic association study using five tag SNPs fully covering the STAT-1 gene in a Dutch cohort of 355 independent CD cases and 360 healthy controls. Neither the alleles, nor the genotypes in the case-control genetic association studies, nor the haplotype analysis showed any association to the STAT-1 gene in the Dutch CD population. Our results do not point to a primary involvement of the STAT-1 gene in the Dutch CD population.

Genetic and functional analysis of pyroglutamyl-peptidase I in coeliac disease.

Coeliac disease (CD) is an enteropathy caused by an immune reaction towards wheat gluten and similar proteins from barley and rye. It was shown that some gluten peptides spontaneously form N-terminal L-pyroglutamate. This modification could potentially make gluten more resistant to proteolytic degradation within the intestine. Pyroglutamyl-peptidase I (PGPEPI) is an enzyme that hydrolytically removes the L-pyroglutamyl residues that render the modified proteins and peptides more sensitive to degradation by other proteases. Interestingly, we found that the PGPEP1 gene is located in a CD susceptibility locus. As an impaired enzyme function caused by genetic alterations might increase the amount of immunogenic gluten peptides, we conducted a comprehensive functional genomics analysis of PGPEP1, including DNA sequencing, genetic association testing, and quantifying RNA expression. We also determined the enzymatic activity of PGPEPI in duodenal biopsies. Our results uniformly indicate that PGPEP1 is not involved in the aetiology and pathology of CD.

No genetic association of the human prolyl endopeptidase gene in the Dutch celiac disease population.

Celiac disease (CD) is a complex genetic disorder of the small intestine. The DQ2/DQ8 human leucocyte antigen (HLA) genes explain approximately 40% of the genetic component of the disease, but the remaining non-HLA genes have not yet been identified. The key environmental factor known to be involved in the disease is gluten, a major protein present in wheat, barley, and rye. Integrating microarray data and linkage data from chromosome 6q21-22 revealed the prolyl endopeptidase (PREP) gene as a potential CD candidate in the Dutch population. Interestingly, this gene encodes for the only enzyme that is able to cleave the proline-rich gluten peptides. To investigate the role of the human PREP gene as a primary genetic factor in CD, we conducted gene expression, sequence analysis, and genetic association studies of the PREP gene and determined PREP enzyme activity in biopsies from CD patients and controls. Sequence analysis of the coding region of the PREP gene revealed two novel polymorphisms. Genetic association studies using two novel polymorphisms and three known PREP variants excluded a genetic association between PREP and CD. Determination of PREP activity revealed weak but significant differences between treated and untreated CD biopsies (P < 0.05). Our results from the association study indicate that PREP is not a causative gene for CD in the Dutch population. These are further supported by the activity determinations in which we observed no differences in PREP activity between CD patients and controls.