Immunoglobulin G autoantibodies against tissue-transglutaminase. A sensitive, cost-effective assay for the screening of celiac disease.

The characterization of target antigens in several autoimmune disorders has made it possible to develop antigen-specific immunoassays that are superior in terms of sensitivity, specificity, reproducibility and ease of standardization, compared to immunohistological methods that are highly subjective, rely on skilled technicians and are not applicable to large-scale studies. In the case of celiac disease (CD), tissue transglutaminase (tTGase) has been identified as a major autoantigen, and antibodies against this molecule are present in most CD patients before gluten is removed from diet. In general, anti-tTGase detection assays detect the presence of IgA class antibodies, but these immunoglobulins are absent among patients with IgA deficiency, a frequent condition in which CD is very prevalent. In this report, we have analyzed 64 patients at diagnosis of CD for the presence of antibodies against tTGase of both IgA (TGA) and IgG (TGG) classes, using anti-IgA antibodies or Protein A, respectively, for the immunoprecipitation of 35S labeled, in vitro transcribed and translated human recombinant tTGase. In our hands, the TGG assay matches TGA in terms of sensitivity (97%) and specificity (100%), and besides, the combination of both assays is able to detect antibodies in all patient samples. The method described uses only 6 microl of serum, can be adapted to automated large-scale analysis and, in combination with other antigens, can be used for the simultaneous screening of other autoimmune diseases, like type 1 diabetes mellitus.

Prospective population screening for celiac disease: high prevalence in the first 3 years of life.

BACKGROUND: Celiac disease (CD) is an autoimmune enteropathy that develops in genetically susceptible individuals exposed to gliadin. Early diagnosis of CD may reduce the risk of complications, and several studies have related the duration of gluten exposure to the risk of other autoimmune diseases. It has been proposed that silent CD be diagnosed as soon as possible to avoid potential complications. OBJECTIVES: The purpose of this study was to determine the prevalence of CD among children less than 3 years and to provide treatment to those patients diagnosed with CD. PATIENTS AND METHODS: Parents of 1100 healthy children born between October 1998 and December 1999 were asked at the time of delivery to enroll their children in a program for the early diagnosis of CD. The parents of 830 children agreed to participate. Patients in the study were examined and anti-tissue transglutaminase antibody was first measured at about 1.5 years of age. A second antibody titer was obtained at about 2.5 years of age. Patients with detectable autoantibodies underwent intestinal biopsy for confirmation of CD. RESULTS: Of the 830 children initially enrolled, 613 and 484 returned for the first and second visits, respectively. None had anti-tissue transglutaminase antibodies at the first visit, but 9 had anti-tissue transglutaminase immunoglobulins at the second visit. In 7 of these 9, intestinal biopsy confirmed the diagnosis of CD which suggests a minimum prevalence of CD of 1 per 118 healthy newborns. CONCLUSIONS: The authors observed a very high prevalence of CD, comparable to that observed in other European populations, which might even be higher if all of the children initially examined had returned for their second visit. If general screening for CD were accepted, the authors would recommend age 2-3 years as the best time for measuring tissue transglutaminase antibodies.

No association of CTLA4 gene with celiac disease in the Basque population.

BACKGROUND: Celiac disease (CD) is an autoimmune disorder caused by intolerance to ingested gluten that develops in genetically susceptible individuals. The contribution of human leukocyte antigen (HLA) genes to the genetic risk to CD has been known for a long time; however, non-HLA genetic factors are likely to be required for the development of the disease. Several studies have associated the CD28/CTLA4 region on chromosome 2q33 with the disease in different populations. The CTLA4 gene encodes a receptor involved in the control of T-cell proliferation and mediates T-cell apoptosis. AIM To determine the contribution of two polymorphisms of the CTLA4 to the disease: the A/G dimorphism at position +49 in exon 1 and the (AT)(n) microsatellite in the 3' untranslated region. PATIENTS: Forty-one celiac families of Basque origin (43 patients with CD and 80 first-degree relatives). METHODS: Restriction enzyme digestion of polymerase chain reaction amplified genomic DNA for the A/G dimorphism and polymerase chain reaction followed by high-resolution electrophoresis for the (AT)(n) microsatellite. For disease association studies, the Affected Family Based Controls approach was used. RESULTS: The frequency of the A allele of 49 A/G polymorphism was 67.47% in the celiac allele group compared with 70.13% in the Affected Family Based Controls group. These differences were not significant. Analysis of the (AT)(n) polymorphism identified 17 different alleles, ranging from 262 to 312 bp in length, but no allele was significantly associated with the disease. CONCLUSIONS: Our results did not show any evidence of association of any of the CTLA4 gene polymorphisms with the disease. This may result from population-specific differences in genetics and environmental susceptibility to CD.