Genetic susceptibility of human leukocyte antigen alleles in chronic inflammatory demyelinating polyneuropathy in Korean patients: Short title: HLA alleles and CIDP in Korea

Background: The pathogenesis of chronic inflammatory demyelinating polyneuropathy (CIDP) is still not fully understood, but HLA polymorphisms have been implicated in immunogenesis. In the present study, we aimed to identify HLA alleles susceptible to CIDP in the Korean population. Methods: We retrospectively analyzed 27 Korean patients with CIDP diagnosed at Samsung Medical Center between 2016 and 2022. Clinical features and nodal/paranodal antibodies were assessed. HLA-DRB1, DPB1, and DQB1 genotyping was performed using the Luminex-based oligonucleotide probe method. Autoimmune nodopathy (AN) was defined by the presence of anti-NF155, anti-contactin-1, or anti-CASPR1 antibodies confirmed by cell-based assay. Allele frequencies were compared with those from 173 healthy Korean controls. Statistical analyses included chi-square or Fisher’s exact tests, Cohen’s h, post-hoc power analysis, and Hochberg correction for multiple comparisons. Haplotype frequencies were estimated using the expectation-maximization algorithm. Results: The median age of the patients was 58 years, and 12 (44.4%) were female. Anti-NF155 antibodies were identified in 7 of 27 patients (25.9%). DRB1*04 frequency was significantly higher in patients compared to controls (27.8% vs. 2.6%, p-value < 0.001), with an odds ratio of 14.40 (95% CI 5.91–35.08). This association remained significant in both CIDP and AN subgroups after correction for multiple comparisons. In subgroup comparisons, DRB1*07, DRB1*15, and DQB1*04 were more frequent in AN than in CIDP, but the differences were not statistically significant. Conclusion: Our findings suggest that HLA-DRB1*04 is more frequent in Korean patients with CIDP and AN compared to healthy controls. Further studies with larger cohorts are warranted to validate these observations.