Genome-Wide Association Study Identifies IFIH1 and HLA-DQB1*05:02 Loci Associated With Anti-NMDAR Encephalitis.

BACKGROUND AND OBJECTIVES: Anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis is a rare autoimmune neurologic disorder, the genetic etiology of which remains poorly understood. Our study aims to investigate the genetic basis of this disease in the Chinese Han population. METHODS: We performed a genome-wide association study and fine-mapping study within the major histocompatibility complex (MHC) region of 413 Chinese patients with anti-NMDAR encephalitis recruited from 6 large tertiary hospitals and 7,127 healthy controls. RESULTS: Our genome-wide association analysis identified a strong association at the IFIH1 locus on chromosome 2q24.2 (rs3747517, p = 1.06 × 10-8, OR = 1.55, 95% CI, 1.34-1.80), outside of the human leukocyte antigen (HLA) region. Furthermore, through a fine-mapping study of the MHC region, we discovered associations for 3 specific HLA class I and II alleles. Notably, HLA-DQB1*05:02 (p = 1.43 × 10-12; OR, 2.10; 95% CI 1.70-2.59) demonstrates the strongest association among classical HLA alleles, closely followed by HLA-A*11:01 (p = 4.36 × 10-7; OR, 1.52; 95% CI 1.29-1.79) and HLA-A*02:07 (p = 1.28 × 10-8; OR, 1.87; 95% CI 1.50-2.31). In addition, we uncovered 2 main HLA amino acid variation associated with anti-NMDAR encephalitis including HLA-DQß1-126H (p = 1.43 × 10-12; OR, 2.10; 95% CI 1.70-2.59), exhibiting a predisposing effect, and HLA-B-97R (p = 3.40 × 10-8; OR, 0.63; 95% CI 0.53-0.74), conferring a protective effect. Computational docking analysis suggested a close relationship between the NR1 subunit of NMDAR and DQB1*05:02. DISCUSSION: Our findings indicate that genetic variation in IFIH1, involved in the type I interferon signaling pathway and innate immunity, along with variations in the HLA class I and class II genes, has substantial implications for the susceptibility to anti-NMDAR encephalitis in the Chinese Han population.

Association study of lamotrigine-induced cutaneous adverse reactions and HLA-B*1502 in a Han Chinese population.

Antiepileptic drugs including lamotrigine (LTG) and carbamazepine (CBZ) are among the most common causes of cutaneous adverse reactions (cADRs). Human leukocyte antigen (HLA)-B*1502 has been strongly associated with CBZ-induced Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). To investigate this relationship, we performed high-resolution HLA genotyping on LTG-tolerant controls, healthy volunteers, and patients affected by LTG-induced cADRs, ranging from maculopapular exanthema (MPE) to SJS/TEN. Patients with LTG-induced cADRs (n=25, including three with SJS/TEN and 22 with MPE), 21 LTG-tolerant controls, and 71 healthy volunteers were enrolled. The differences in the starting dosage of LTG among the SJS/TEN, MPE, and LTG-tolerant control groups were not statistically significant. HLA-B*1502 frequency was 33.3% (1/3; LTG-induced SJS/TEN group), 9.1% (2/22; LTG-induced MPE group), 4.8% (1/21; LTG-tolerant group), and 8.5% (6/71; healthy volunteers). There was no significant difference in the frequency of subjects with the HLA-B*1502 allele between the SJS/TEN group and LTG-tolerant group (p=0.239, OR=10.0, 95% CI 0.44-228.7), and healthy volunteers (p=0.26, OR=5.42, 95% CI 0.43-68.8), MPE and LTG-tolerant groups (p=1.0, OR=1.08, 95% CI 0.20-5.8), and healthy volunteers (p=1.0, OR=2.0, 95% CI 0.17-23.9). None of the HLA alleles detected were associated with LTG-induced cADRs. In conclusion, HLA-B*1502 and other HLA alleles are not directly associated with LTG-induced MPE. The possibility that HLA-B*1502 is associated with an increased risk of LTG-induced SJS/TEN could not be excluded.