- The study group consisted of celiac patients following a GFD for at least one year prior to the inclusion in the study and they were required to have an HLA-DQ2 or HLA-DQ8 haplotype and an histologically abnormal duodenal biopsy (grade Marsh IIIB or IIIC) at the time of diagnosis, supported by positive serum anti-endomysium IgA antibodies and/or anti-tissue transglutaminase (anti-tTG) IgA antibodies.