1282-P: Genetic Susceptibility of Dipeptidyl Peptidase-4 Inhibitor–Associated Bullous Pemphigoid in Chinese Patients with Type 2 Diabetes

Objective: The rare risk association of bullous pemphigoid (BP) with use of dipeptidyl peptidase-4 inhibitors (DPP-4i) had been reported including genetic association with HLA variants. We assessed genetic susceptibility of BP associated with DPP-4i use in patients with type 2 diabetes (T2D) .

Methods: In a prospective cohort of 30,129 Chinese patients with T2D enrolled in the Hong Kong Diabetes Register between 1995 to 2018, we curated multiple case-control cohorts with available genotype data to explore the genetic associations of major histocompatibility complex (MHC) region with DDP-4i-associated BP.

Results: During a median follow period of 9 years, 60 patients developed BP (incidence of 2.cases per 10,000 patient-years) . 20 patient developed BP after DPP-4i use, with median exposure to DPP-4i of 1.7 years (incidence of 4.76 cases per 10,000 patient-years) and an adjusted odds ratio of 1.1 (95% CI 0.5-1.6) . 32 patients developed BP and were not exposed to DPP-4i (incidence of 2.87 cases per 10,000 patient-years) . In 1:2 matched case:control cohort of patients who tolerated DPP-4i and did not develop of BP, multiple variants in the second intron of HLA-DQB1 exhibited strong association with DPP4i-associated BP, including the well-reported HLA-DQB1*03: (OR 12.00; 95% CI 1.99-72.35; P-value 6.71e-03) and a novel single nucleotide polymorphism rs281863580 (OR 11.96; 95% CI 4.14-34.54; P-value 4.53e-06) . We additionally identified variants located in other HLA regions that were associated with BP in non-DPP4i users.

Conclusion: Multiple genetic polymorphisms in the second intron of HLA-DQB1 were associated with increased susceptibility to incident BP in DPP-4i users. Further exploration of the extended MHC region beyond HLA alleles might identify a combination panel for assessing the genetic risk of BP rather than a single HLA allele.