Pathophysiological similarities between latent autoimmune diabetes in adults (LADA) and type 1 diabetes indicate an overlap in genetic susceptibility. HLA-DRB1 and HLA-DQB1 are major susceptibility genes for type 1 diabetes but studies of these genes in LADA have been limited. Our aim was to define patterns of HLA-encoded susceptibility/protection in a large, well characterised LADA cohort, and to establish association with disease and age at diagnosis.
Materials and methods
Patients with LADA (n=387, including 211 patients from the UK Prospective Diabetes Study) and non-diabetic control subjects (n=327) were of British/Irish European origin. The HLA-DRB1 and -DQB1 genes were genotyped by sequence-specific PCR.
As in type 1 diabetes mellitus, DRB1*0301_DQB1*0201 (odds ratio [OR]=3.08, 95% CI 2.32–4.12, p=1.2× 10−16) and DRB1*0401_DQB1*0302 (OR=2.57, 95% CI 1.80–3.73, p=4.5×10−8) were the main susceptibility haplotypes in LADA, and DRB1*1501_DQB1*0602 was protective (OR=0.21, 95% CI 0.13–0.34, p=4.2×10−13). Differential susceptibility was conferred by DR4 subtypes: DRB1*0401 was predisposing (OR=1.79, 95% CI 1.35–2.38, p=2.7×10−5) whereas DRB1*0403 was protective (OR=0.37, 95% CI 0.13–0.97, p=0.033). The highest-risk genotypes were DRB1*0301/DRB1*0401 and DQB1*0201/DQB1*0302 (OR=5.14, 95% CI 2.68–10.69, p=1.3×10−8; and OR=6.88, 95% CI 3.54–14.68, p=1.2×10−11, respectively). These genotypes and those containing DRB1*0401 and DQB1*0302 associated with a younger age at diagnosis in LADA, whereas genotypes containing DRB1*1501 and DQB1*0602 associated with an older age at diagnosis.
Patterns of susceptibility at the HLA-DRB1 and HLA-DQB1 loci in LADA are similar to those reported for type 1 diabetes, supporting the hypothesis that autoimmune diabetes occurring in adults is an age-related extension of the pathophysiological process presenting as childhood-onset type 1 diabetes.