<scp>HLA</scp> Class I Haplotype in Glutamic Acid Decarboxylase Antibody‐Associated Neurological Disease

OBJECT: Glutamic acid decarboxylase antibody-associated neurological disease (GADAND) is a rare autoimmune disorder with elusive immunogenetic underpinnings. We aimed to investigate HLA associations with GADAND susceptibility in a Chinese cohort. METHODS: We performed HLA genotyping at the HLA-A, -B, -C, -DRB1, -DQA1, and -DQB1 loci in 62 Chinese patients with GADAND and compared them with 990 healthy controls. Haplotype frequencies were estimated using the expectation-maximization (EM) algorithm. Allele and haplotype associations with disease susceptibility and clinical phenotypes were assessed. RESULTS: = 0.829), were more frequent in GADAND patients, and A*11:01 ~ B*40:01 ~ C*07:02 was enriched in those with comorbid AITD. No statistically significant associations were identified between HLA haplotypes and clinical phenotypes. CONCLUSIONS: The haplotype A*11:01 ~ B*40:01 ~ C*07:02 was associated with GADAND susceptibility in the Chinese population, implicating T cell involvement. T1DM-associated haplotypes were overrepresented in GADAND, and A*11:01 ~ B*40:01 ~ C*07:02 was enriched in comorbid AITD, suggesting HLA as a shared immunogenetic basis for autoimmune comorbidities. No significant HLA associations with clinical phenotypes were identified, warranting validation in larger cohorts.