Background: 

Autoantibodies against β-cell components in the pancreatic islets of Langerhans are characteristic of type 1 diabetes (T1D). The genetic and autoimmune determinants of type 1 diabetes (T1D) in Ethiopians are not yet thoroughly characterized, with studies indicating a lower occurrence of autoantibodies related to T1D compared to Caucasians. The study aimed to determine the occurrence of autoantibodies related to type 1 diabetes (T1D), celiac disease (CD), and autoimmune thyroid disease (AITD) in conjunction with Human Leukocyte Antigen (HLA) genotype in Ethiopian children and adolescents with T1D.

Methods: 

This cross-sectional study included 206 children and adolescents with T1D (ranging from 1 to 18 years old) with a median disease duration of 6 years, alongside 200 age-matched control children (ranging from 1 to 6 years old). Participants were recruited from Adama, Asella, and Bishoftu Hospitals in Ethiopia. The study involved genotyping of HLA alleles, specifically HLA-DQA1, DQB1, and DRB1 ^∗04 (including DR4 subtypes). Additionally, autoantibodies targeting glutamic acid decarboxylase (GADA), insulinoma-associated protein (IA-2A), zinc transporter 8 (ZnT8A), tissue transglutaminase (tTGA), and thyroid peroxidase (TPOA) were analyzed using antibody detection by agglutination PCR (ADAP) assays.

Results: 

The most common haplotype found in participants with T1D was HLA-(DR3)-DQA1 ^∗05-DQB1 ^∗02 haplotype (36.4%) (OR = 5.0; p  < 0.000001). In addition, HLA-DRB1 ^∗0405-DQA1 ^∗03-DQB1 ^∗02 (19.3%, OR = 10.8; p  < 0.000001), HLA-DRB1 ^∗0405-DQA1 ^∗03-DQB1 ^∗0302 (9.2%, OR = 3.1; p = 0.001), and HLA-DRB1 ^∗0401-DQA1 ^∗03-DQB1 ^∗0302 (3.2%, OR = 20.0; p = 0.002) were significantly increased among T1D patients. Conversely, HLA-(DR15)-DQB1 ^∗0602, HLA-(DR13)-DQB1 ^∗0603, HLA-(DR1/10)-DQB1 ^∗0501, HLA-(DR13)-DQB1 ^∗0604, HLA-DRB1 ^∗0404-DQA1 ^∗03-DQB1 ^∗04, HLA-(DR7)-DQA1 ^∗0201-DQB1 ^∗02, HLA-(DR11/12/13)-DQA1 ^∗05-DQB1 ^∗0301, and HLA-DRB1 ^∗0403-DQA1 ^∗03-DQB1 ^∗0302 were noted as the most protective haplotypes with a significant p value and, with ORs ranging from 0.05 to 0.5. The overall frequency of any islet autoantibodies in children and adolescents with T1D was 81.1% compared to 5.5% in the control group (p  < 0.0001). While comparing antibody positivity between individuals with T1D and controls, GADA was found in 69% versus 2%, IA-2A in 24% versus 1.5%, ZnT8A in 32% versus 2%, tTGA in 14% versus 2%, and TPOA in 17% versus 5%, respectively (p  < 0.0001). Individuals carrying DR4-DQ8 or DR3-DQ2 haplotypes exhibited a higher prevalence of IA-2A and tTGA (p ≤ 0.05).

Conclusions: 

The HLA risk profile typical of sub-Saharan African population was observed in Ethiopians with T1D. Furthermore, they have a notably high prevalence of autoantibodies associated with T1D, CD, and AITD, which differs from earlier reports from the region but aligns with patterns observed in Caucasians.