Differences in inflammatory bowel disease phenotype between South Asians and Northern Europeans living in North West London, UK.

OBJECTIVES: The incidence and prevalence of inflammatory bowel disease (IBD) is increasing throughout Asia. Since the 1950s, there has been substantial migration from South Asia (India, Pakistan, and Bangladesh) to the United Kingdom. The aim of this study was to define the clinical phenotype of IBD in UK South Asians living in North West London, and to compare the results with a white Northern European IBD cohort. METHODS: The phenotypic details of 367 South Asian IBD patients (273 ulcerative colitis (UC) and 94 Crohn's disease (CD)), undergoing active follow-up in five North West London hospitals, were compared with those of 403 consecutively collected white Northern European IBD patients (188 UC and 215 CD). RESULTS: The phenotype of IBD differed significantly between the two populations. 63.0% of South Asian UC patients had extensive colitis compared with 42.5% of the Northern European cohort (P < 0.0001). Proctitis was uncommon in South Asian UC patients (9.9 vs. 26.1% in Northern European patients, P<0.0001). In the South Asian CD cohort, disease location was predominantly colonic (46.8%). CD behavior differed significantly between the groups, with less penetrating disease compared with Northern Europeans (P=0.01) and a reduced need for surgery (P=0.003). CONCLUSIONS: The phenotype of IBD in South Asians living in North West London is significantly different from that of a white Northern European IBD cohort. Knowledge of ethnic variations in disease phenotype may help to identify key genetic, environmental, and behavioral factors contributing to the development of IBD.

Anti-tissue transglutaminase antibodies in coeliac disease are not a response to gut damage alone.

BACKGROUND: Anti-tissue transglutaminase (tTG) antibody is being used increasingly as a diagnostic tool in the serological investigation of coeliac disease. However, positive predictive values of immunoglobulin A anti-tTG for coeliac disease in prospective studies have been disappointing. OBJECTIVE: To determine whether anti-tTG can arise as a non-specific consequence of abnormal gut permeability. PATIENTS: A cohort from routine investigation for possible gluten-sensitive enteropathy, with 44 cases selected based on whether permeability studies had been performed. METHODS: The cohort was assessed for anti-tTG by enzyme-linked immunosorbent assay, small-bowel biopsy and C-mannitol absorbency. RESULTS: Eighteen of the 44 patients had biopsy-proven coeliac disease and 23 showed abnormal permeability. There was poor correlation between the level of anti-tTG and gut permeability. CONCLUSIONS: These data confirm an association between anti-tTG and coeliac disease but no clear relationship with other forms of increased gut permeability.

Is immunoglobulin A anti-tissue transglutaminase antibody a reliable serological marker of coeliac disease?

BACKGROUND: Anti-tissue transglutaminase (tTG) antibody is being used increasingly as a diagnostic tool in the serological investigation of coeliac disease. However, positive predictive values of immunoglobulin A (IgA) anti-tTG for coeliac disease in prospective studies have been disappointing and false-positive results are reported. OBJECTIVE: To assess the clinical utility of cascade testing for anti-tTG and anti-endomysium antibody (AEA). PATIENTS: Two unselected retrospective cohorts from routine diagnostic investigation for possible gluten sensitive enteropathy: group 1 comprised 57 cases seropositive for anti-tTG and group 2 comprised 52 cases seronegative for anti-tTG. In both groups, all cases had also undergone small-intestinal biopsy. METHODS: Patients were assessed for the presence of IgA anti-tTG by enzyme-linked immunosorbent assay and for IgA AEA by immunofluorescence. RESULTS: The positive predictive value of IgA anti-tTG for biopsy-confirmed coeliac disease was 54%. The positive predictive value of dual positivity for anti-tTG and AEA was 97%. The negative predictive value of IgA anti-tTG was 100%. CONCLUSIONS: The data presented here support the use of IgA anti-tTG as an initial screen for coeliac disease. Coeliac disease is unlikely when IgA anti-tTG is absent. However, many false-positive results are seen, and clinical utility and diagnostic efficiency are improved markedly if positive results are confirmed with the more accurate, but labour-intensive, AEA assay.