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.

HLA-A*24:02 as a common risk factor for antiepileptic drug-induced cutaneous adverse reactions.

OBJECTIVE: To investigate the involvement of human leukocyte antigen (HLA) loci in aromatic antiepileptic drug-induced cutaneous adverse reactions. METHODS: A case-control study was performed to detect HLA loci involved in aromatic antiepileptic drug-induced Stevens-Johnson syndrome in a southern Han Chinese population. Between January 1, 2006, and December 31, 2015, 91 cases of Stevens-Johnson syndrome induced by aromatic antiepileptic drugs and 322 matched drug-tolerant controls were enrolled from 8 centers. Important genotypes were replicated in cases with maculopapular eruption and in the meta-analyses of data from other populations. Sequence-based typing determined the HLA-A, HLA-B, HLA-C, and HLA-DRB1 genotypes. RESULTS: HLA-B*15:02 was confirmed as strongly associated with carbamazepine-induced Stevens-Johnson syndrome (p = 5.63 × 10-15). In addition, HLA-A*24:02 was associated significantly with Stevens-Johnson syndrome induced by the aromatic antiepileptic drugs as a group (p = 1.02 × 10-5) and by individual drugs (carbamazepine p = 0.015, lamotrigine p = 0.005, phenytoin p = 0.027). Logistic regression analysis revealed a multiplicative interaction between HLA-B*15:02 and HLA-A*24:02. Positivity for HLA-A*24:02 and/or HLA-B*15:02 showed a sensitivity of 72.5% and a specificity of 69.0%. The presence of HLA-A*24:02 in cases with maculopapular exanthema was also significantly higher than in controls (p = 0.023). Meta-analysis of data from Japan, Korea, Malaysia, Mexico, Norway, and China revealed a similar association. CONCLUSIONS: HLA-A*24:02 is a common genetic risk factor for cutaneous adverse reactions induced by aromatic antiepileptic drugs in the southern Han Chinese and possibly other ethnic populations. Pretreatment screening is recommended for people in southern China.

Levetiracetam-induced cutaneous adverse drug reactions were not associated with HLA genes in a small sample of Chinese patients with epilepsy.

PURPOSE: This study aimed to evaluate the clinical characteristics of levetiracetam (LEV)-induced cutaneous adverse drug reactions (cADRs) and to explore its possible genetic association with the human leukocyte antigen (HLA) genes. METHODS: Nine cases with LEV-induced cADRs were recruited. Demographic and clinical information of these cases was summarized. Additionally, cases were matched with LEV-tolerant controls (1:4). High-resolution HLA class I and class II genotyping was performed for each participant. The allele frequencies between the cases and controls were compared. RESULTS: All LEV-induced cADRs were mild skin rashes which occurred within 28 days of LEV exposure. The mean latency from LEV exposure to skin rash was (15.67±5.41) days (ranging 6-27). The carrier rates of the two alleles, HLA-DRB1*0405 and HLA-DQB1*0401, were higher in cases compared with controls (the same P=0.036, OR=13.875, 95% CI: 1.273-151.230). The association between the HLA-C*0304 allele and LEV-induced cADRs was boundary (P=0.05, OR=5.2, 95% CI: 1.086-24.897). However, the above-mentioned HLA alleles didn't reach statistical significance after multiple comparisons. CONCLUSIONS: Safety monitoring was necessary within four weeks after the initiation of LEV treatment, although it has been regarded as a safe antiepileptic drug. Our study failed to show any potential link between HLA alleles and LEV-induced cADRs in Han Chinese. Further studies are needed to clarify the genetic and immunological mechanisms of LEV-induced cADRs.

Genetic predictors of Stevens-Johnson syndrome and toxic epidermal necrolysis induced by aromatic antiepileptic drugs among the Chinese Han population.

BACKGROUND: Previous studies suggested that one or more HLA alleles participate in the pathogenesis of AED-induced SJS/TEN, but most of these studies focused only on the HLA-B alleles. PURPOSE: The aim of this study was to investigate the pathogenesis of AED-induced SJS/TEN across a broader spectrum of HLA alleles, including the HLA-A, -B and -DRB1 alleles, to further explore the association between each HLA allele and SJS/TEN induced by aromatic AEDs. METHODS: A total of 27 patients exhibiting AED-induced SJS/TEN (16 CBZ-SJS/TEN, seven LTG-SJS/TEN, two PHT-SJS/TEN, and two PB-SJS/TEN patients) and 64 patients who exhibited tolerance to AEDs were recruited. High-resolution HLA genotyping was performed to estimate the prevalence of the HLA-A, -B and -DRB1 alleles for each subject. RESULTS: Fifteen subjects in the SJS/TEN group (12 exhibiting CBZ-SJS/TEN, two exhibiting LTG-SJS, and one exhibiting PB-SJS) carried the HLA-B*15:02 allele, whereas only 4/64 subjects in the AED-tolerant group carried this allele; the carrier rate of HLA-B*15:02 was significantly different between the groups (P<0.001). Nine patients in the SJS/TEN group carried the HLA-DRB1*15:01 allele, while 12/64 subjects in the tolerant group carried this allele; considering that two patients in the SJS/TEN group (one exhibiting LTG-SJS and one exhibiting PB-SJS) were homozygous for this allele, the prevalence of HLA-DRB1*15:01 expression between the two groups was significantly different (P=0.041). Furthermore, the carrier rates of HLA-A*33:03, HLA-B*58:01, and HLA-DRB1*03:01 were lower in the SJS/TEN group compared with the AED-tolerant group. The carrier rates of these alleles between the two groups were significantly different (P=0.009, 0.016, and 0.009, respectively). CONCLUSIONS: The HLA-DRB1*15:01 allele may represent a risk factor for AED-induced SJS/TEN among Han Chinese. The HLA-A*33:03, HLA-B*58:01, and HLA-DRB1*03:01 alleles may be "protectors" against AED-induced SJS/TEN, especially CBZ-SJS/TEN.

Genetic susceptibility to the cross-reactivity of aromatic antiepileptic drugs-induced cutaneous adverse reactions.

BACKGROUND: The cross-allergic reactions among aromatic antiepileptic drugs (AEDs) are common, but little is known about the genetic mechanisms. PURPOSE: The aim of this study was to investigate the genetic associations of the human leukocyte antigen (HLA) genes with the cross-reactivity of cutaneous adverse drug reactions (cADRs) induced by different aromatic AEDs. METHODS: We reviewed 60 Chinese patients with a history of cADRs induced by an aromatic AED, and which re-challenged other aromatic AEDs as an alternative to the causative AED owing to some particular reasons. According to whether developing another episode of cADRs, these patients were automatically divided into the cross-reactivity group and tolerant control group. High-resolution HLA-A, -B, -DRB1 genotyping were performed for each patient. RESULTS: One out of 10 patients (10%, 1/10) carried the HLA-A*2402 allele in the cross-reactivity group. However, 23 patients (46%, 23/50) carried this allele in the tolerant control group. The difference of the HLA-A*2402 allele between the two groups is statistically significant (P=0.040, OR=0.130, 95% CI: 0.015-1.108). In addition, the frequency differences of other HLA alleles between the two groups, including the HLA-B*1502 allele, did not reach statistical significance (P>0.05). CONCLUSIONS: The HLA genes contribute to the genetic susceptibility of the cross-reactivity of cADRs among aromatic AEDs. Our results suggest that HLA-B*1502 is not a major responsible allele for the cross-reactivity of cADRs to aromatic AEDs, but the HLA-A*2402 allele may be a protective marker for the cross-allergic reactions among aromatic AEDs in Han Chinese. Further studies are warranted to test the potential predictive value of the HLA-A*2402 allele in future.

Predictive markers for carbamazepine and lamotrigine-induced maculopapular exanthema in Han Chinese.

The aims of this study were to clarify the possible associations of carbamazepine (CBZ)- and lamotrigine (LTG)-induced maculopapular exanthema (MPE) with the human leukocyte antigen (HLA) alleles in Chinese patients. A total of 249 subjects, including 40 patients with CBZ-induced MPE (CBZ-MPE), 43 patients with LTG-induced MPE (LTG-MPE), 52 CBZ-tolerant controls, 42 LTG-tolerant controls and 72 healthy controls, were included in this study. High-resolution HLA genotyping was performed by a specific kit. Differences in the allele frequencies among the groups were assessed. The allele frequencies of HLA-A*0201 and HLA-DRB1*1405 were significantly higher (P=0.033 and P=0.003, respectively), but those of HLA-B*5801 and HLA-DRB1*0301 (P=0.037 and P=0.024, respectively) were lower in the CBZ-MPE patients when compared with the CBZ-tolerant group. We also observed two significantly increased alleles of HLA-A*3001 and HLA-B*1302 (P=0.013 and P=0.013, respectively) and a decreased allele of HLA-A*3303 (P=0.048) in the LTG-MPE patients when compared with those in the LTG-tolerant group. Our results support the hypothesis that these HLA alleles contribute to the genetic susceptibility to CBZ/LTG-MPE and may be valuable as potential biomarkers for CBZ/LTG-MPE in Han Chinese.

Phenytoin-induced Stevens-Johnson syndrome with negative HLA-B*1502 allele in mainland China: two cases.

Antiepileptic drugs-induced Stevens-Johnson syndrome (SJS) is a life-threatening severe cutaneous adverse reaction. Recent studies in Thailand and Taiwan showed a significant association between phenytoin (PHT)-induced SJS and human leucocyte antigen HLA-B*1502 allele. Although the US FDA had issued an alert to clinicians, insufficient information is available to recommend testing for HLA-B*1502 in Asian patients in line for PHT treatment. Therefore, extended studies are necessary to further evaluate the potential association between PHT-induced SJS and HLA-B*1502 allele in various populations. To date, no similar data exist in mainland China. Here, we describe two Chinese Han cases of PHT-induced SJS with negative HLA-B*1502 allele, in which HLA high-resolution genotyping showed two heterozygous HLA-B*4601/B*5102 and HLA-B*3701/B*4601 allele, respectively. Our findings provide evidence to support that other genetic markers or nongenetic factors could contribute to the susceptibility of PHT-induced SJS, except for HLA-B*1502 allele. Further studies are encouraged to investigate the genetic link with PHT-induced serious skin reactions in future.

Pilot association study of oxcarbazepine-induced mild cutaneous adverse reactions with HLA-B*1502 allele in Chinese Han population.

BACKGROUND: Recent study demonstrated that HLA-B*1502 was a common risk allele in aromatic antiepileptic drugs (AEDs) induced Stevens-Johnson syndrome and toxic epidermal necrolysis in Han Chinese. However, the association of AEDs-induced mild maculopapular eruption (MPE) with HLA-B*1502 remains unclear until recently. In the present study, we conducted a pilot study to detect a possible association of oxcarbazepine (OXC)-induced MPE with HLA-B*1502 allele in Chinese Han population. METHODS: We enrolled 90 subjects involving 9 patients with OXC-induced MPE and two groups of controls, 9 OXC-tolerant and 72 normal controls. High-resolution HLA genotyping was performed by specific kit. The results of HLA genotyping are expressed as positive or negative for HLA-B*1502 allele. Differences in genotype frequencies between groups were assessed by the Fisher's exact test. RESULTS: Four cases were detected as positive for HLA-B*1502 amongst 9 patients. However, only 1 subject was positive amongst 9 tolerant controls, and 6 subjects were positive amongst 72 normal controls. The difference in HLA-B*1502 allele frequencies between the MPE group and normal controls was statistically significant (OR: 8.8; 95% CI: 1.853-41.790; P=0.011). In addition, we also observed an increased frequency of HLA-B*1502 allele in patients (44.44%) compared with tolerant controls (11.11%), although it failed to reach statistical significance (P=0.294). CONCLUSIONS: Our findings indicate that HLA-B*1502 allele may contribute to the genetic susceptibility to OXC-induced MPE in Chinese Han population. In order to safer AEDs use, we recommend that HLA-B*1502 allele should be tested for patients with OXC-induced MPE before changing to other AEDs, and AEDs with similar chemical structure should be avoided in individuals who test positive for HLA-B*1502 allele. It should be pointed out that, however, our results may well be just by chance owing to the small sample size and should be further confirmed in future studies.

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.