Frequency of HLA-DQB1*0201/02 and DQB1*0302 alleles and tissue transglutaminase antibody seropositivity in children with type 1 diabetes mellitus.

BACKGROUND: Patients with type 1 diabetes mellitus (T1DM) have an increased risk of celiac disease (CD). Both diseases have a common genetic susceptibility locus in the human leukocyte antigen (HLA) class II alleles. Testing for tissue transglutaminase antibodies (anti-tTG) is highly accurate for a CD diagnosis.

OBJECTIVE: To determine the frequency of HLA-DQB1*0201/02 and DQB1*0302 alleles and anti-tTG seropositivity in children with T1DM.

METHOD: Forty-six children with T1DM (male:female=24:22; mean age 12±3.7 years) without significant digestive symptoms were enrolled. The mean duration of diabetes was 5±3.5 years. Serum anti-tTG IgA and IgG as well as HLA-DQ2 (DQB1*0201/02) and -DQ8 (DQB1*0302) alleles were analyzed. The allele frequencies were compared with those in controls, which included 124 normal Thai individuals, as reported in our previous study.

RESULTS: All subjects were negative for anti-tTG IgG. Only one patient (2.2%) was positive for anti-tTG IgA (38.5 U/mL; cut-off 15 U/mL). Although this patient was also heterozygous for HLA-DQ2 and was asymptomatic for CD, he declined endoscopic confirmation. Twenty-nine of 46 patients carried HLA-DQ2 and/or -DQ8 heterodimers. HLA-DQB1*0201/02 and HLA-DQB1*0302 allele frequencies were significantly higher (27% and 14%) in T1DM patients compared with normal controls (13.3% and 7.3%; P<0.001 and P=0.002, respectively).

CONCLUSIONS: A significantly greater frequency of DQB1*0201/02 and DQB1*0302 alleles were present in children with T1DM compared with the control group. This indicates a potentially important role of these alleles in the development of T1DM. The prevalence of CD screening by serologic testing is negligible in Thai children with T1DM.