Role of human-tissue transglutaminase IgG and anti-gliadin IgG antibodies in the diagnosis of coeliac disease in patients with selective immunoglobulin A deficiency.
BACKGROUND
Selective IgA deficiency is associated with coeliac disease, and studies have shown an increased prevalence of coeliac disease in these patients ranging from 0.71 to 30.7%, depending on the test used for screening.


OBJECTIVE
To determine the sensitivity of IgG anti-gliadin-antibodies and of IgG human-tissue-transglutaminase for diagnosing coeliac disease and assessing its prevalence in subjects with IgA deficiency.


METHODS
We tested serum samples from 126 IgA-deficient children (66 female, median age: 10.8 years).


METHODS
All samples were analysed to measure IgG anti-gliadin-antibodies and IgG anti-human-tissue-transglutaminase. Patients testing positive to either test underwent intestinal biopsy. Subjects testing positive for IgG anti-human-tissue-transglutaminase underwent genetic testing for the human leucocyte antigen heterodimer.


RESULTS
Twenty-seven of 126 subjects tested positive for IgG anti-gliadin-antibodies (five of whom tested positive also for IgG anti-human-tissue-transglutaminase) and 18 (including the aforementioned five) for IgG anti-human-tissue-transglutaminase. Intestinal biopsy was performed in 37 of the 40 patients who tested positive (three subjects refused). Eleven had positive intestinal biopsies all of whom tested positive for IgG anti-human-tissue-transglutaminase, but only five of these tested positive also for IgG anti-gliadin-antibodies. All 22 patients testing positive for anti-gliadin-antibody alone had normal intestinal mucosa. All the patients who tested positive for IgG anti-human-tissue-transglutaminase and underwent genetic screening (15/18) had the coeliac-related human leucocyte antigen. Overall, coeliac disease was diagnosed in 11 of the 126 subjects with IgA deficiency (8.7%).


CONCLUSIONS
The prevalence of coeliac disease in subjects with total IgA deficiency was 8.7%. Assay of IgG anti-human-tissue-transglutaminase can be recommended for screening coeliac disease in IgA-deficient subjects.
Lenhardt
A
A
Department of Paediatrics, IRCCS Burlo Garofolo, University of Trieste, Via dell'Istria 65/1, 34100 Trieste, Italy.
Plebani
A
A
Marchetti
F
F
Gerarduzzi
T
T
Not
T
T
Meini
A
A
Villanacci
V
V
Martelossi
S
S
Ventura
A
A
D000293:Adolescent; D000328:Adult; D002446:Celiac Disease / Q000097:blood / Q000150:complications* / Q000175:diagnosis* / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D005260:Female; D019204:GTP-Binding Proteins / Q000276:immunology*; D005903:Gliadin / Q000276:immunology*; D006801:Humans; D017098:IgA Deficiency / Q000150:complications*; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D012680:Sensitivity and Specificity; D011503:Transglutaminases / Q000276:immunology*
D007074:Immunoglobulin G; D005903:Gliadin; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins