CCM1 and CCM2 variants in patients with cerebral cavernous malformation in an ethnically Chinese population in Taiwan.

Cerebral cavernous malformation (CCM) is a vascular malformation characterized by clustered enlarged capillary-like channels in the central nervous system. The genes harboring variants in patients with CCM include CCM1/Krev interaction trapped-1, CCM2/MGC4607, and CCM3/programmed cell death protein 10. We aimed to identify pathogenic variants in an ethnic Chinese population in Taiwan. We recruited 95 patients with multiple CCMs or a single lesion with a relevant family history. Sanger sequencing was performed for 41 patients. Variants were identified using sequence alignment tools, and the clinical significance of these variants was determined using American College of Medical Genetics and Genomics standards and guidelines. Several pathogenic variants were found in six patients, including three unrelated patients and three affected members of one family. Two novel pathogenic variants leading to early truncation comprised a deletion variant in exon 18 of CCM1 (c.1846delA; p.Glu617LysfsTer44) and an insertion variant in exon 4 of CCM2 (c.401_402insGCCC; p.Ile136AlafsTer4). One novel pathogenic splice site variant was c.485 + 1G > C at the beginning of intron 8 of CCM1. In this study, we identified novel variants related to CCM in an ethnically Chinese population in Taiwan.

Risk and association of HLA with oxcarbazepine-induced cutaneous adverse reactions in Asians.

OBJECTIVE: To investigate the risk and genetic association of oxcarbazepine-induced cutaneous adverse reactions (OXC-cADRs), including Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN), in Asian populations (Chinese and Thai). METHODS: We prospectively enrolled patients with OXC-cADRs in Taiwan and Thailand from 2006 to 2014, and analyzed the clinical course, latent period, drug dosage, organ involvement, complications, and mortality. We also investigated the carrier rate of HLA-B*15:02 and HLA-A*31:01 of patients with OXC-cADRs and compared to OXC-tolerant controls. The incidence of OXC-SJS/TEN was compared with carbamazepine (CBZ)-induced SJS/TEN according to the nationwide population dataset from the Taiwan National Health Insurance Research Database. RESULTS: We enrolled 50 patients with OXC-cADRs, including 20 OXC-SJS/TEN and 6 drug reaction with eosinophilia and systemic symptoms, of Chinese patients from Taiwan and Thai patients from Thailand. OXC-cADRs presented with less clinical severity including limited skin detachment (all ≦5%) and no mortality. There was a significant association between HLA-B*15:02 and OXC-SJS (p = 1.87 × 10-10; odds ratio 27.90; 95% confidence interval [CI] 7.84-99.23) in Chinese and this significant association was also observed in Thai patients. The positive and negative predictive values of HLA-B*15:02 for OXC-SJS/TEN were 0.73% and 99.97%, respectively. HLA-A*31:01 was not associated with OXC-cADRs. The incidence and mortality of OXC-SJS/TEN was lower than CBZ-STS/TEN in new users (p = 0.003; relative risk 0.212; 95% CI 0.077-0.584). CONCLUSIONS: Our findings suggest that HLA-B*15:02 is significantly associated with OXC-SJS in Asian populations (Chinese and Thai). However, the severity and incidence of OXC-SJS/TEN are less than that of CBZ-SJS/TEN. The need for preemptive HLA-B*15:02 screening should be evaluated further.

Genetic variants associated with phenytoin-related severe cutaneous adverse reactions.

IMPORTANCE: The antiepileptic drug phenytoin can cause cutaneous adverse reactions, ranging from maculopapular exanthema to severe cutaneous adverse reactions, which include drug reactions with eosinophilia and systemic symptoms, Stevens-Johnson syndrome, and toxic epidermal necrolysis. The pharmacogenomic basis of phenytoin-related severe cutaneous adverse reactions remains unknown. OBJECTIVE: To investigate the genetic factors associated with phenytoin-related severe cutaneous adverse reactions. DESIGN, SETTING, AND PARTICIPANTS: Case-control study conducted in 2002-2014 among 105 cases with phenytoin-related severe cutaneous adverse reactions (n=61 Stevens-Johnson syndrome/toxic epidermal necrolysis and n=44 drug reactions with eosinophilia and systemic symptoms), 78 cases with maculopapular exanthema, 130 phenytoin-tolerant control participants, and 3655 population controls from Taiwan, Japan, and Malaysia. A genome-wide association study (GWAS), direct sequencing of the associated loci, and replication analysis were conducted using the samples from Taiwan. The initial GWAS included samples of 60 cases with phenytoin-related severe cutaneous adverse reactions and 412 population controls from Taiwan. The results were validated in (1) 30 cases with severe cutaneous adverse reactions and 130 phenytoin-tolerant controls from Taiwan, (2) 9 patients with Stevens-Johnson syndrome/toxic epidermal necrolysis and 2869 population controls from Japan, and (3) 6 cases and 374 population controls from Malaysia. MAIN OUTCOMES AND MEASURES: Specific genetic factors associated with phenytoin-related severe cutaneous adverse reactions. RESULTS: The GWAS discovered a cluster of 16 single-nucleotide polymorphisms in CYP2C genes at 10q23.33 that reached genome-wide significance. Direct sequencing of CYP2C identified missense variant rs1057910 (CYP2C9*3) that showed significant association with phenytoin-related severe cutaneous adverse reactions (odds ratio, 12; 95% CI, 6.6-20; P=1.1 × 10(-17)). The statistically significant association between CYP2C9*3 and phenytoin-related severe cutaneous adverse reactions was observed in additional samples from Taiwan, Japan, and Malaysia. A meta-analysis using the data from the 3 populations showed an overall odds ratio of 11 (95% CI, 6.2-18; z=8.58; P < .00001) for CYP2C9*3 association with phenytoin-related severe cutaneous adverse reactions. Delayed clearance of plasma phenytoin was detected in patients with severe cutaneous adverse reactions, especially CYP2C9*3 carriers, providing a functional link of the associated variants to the disease. CONCLUSIONS AND RELEVANCE: This study identified CYP2C variants, including CYP2C9*3, known to reduce drug clearance, as important genetic factors associated with phenytoin-related severe cutaneous adverse reactions.

Genotype-phenotype association between HLA and carbamazepine-induced hypersensitivity reactions: strength and clinical correlations.

BACKGROUND: Increasing studies reported genetic susceptibility to drug hypersensitivity reactions, as exemplified by the HLA-A*31:01 and HLA-B*15:02 association with carbamazepine (CBZ)-induced hypersensitivity reactions, such as maculopapular exanthema (MPE), drug rash with eosinophilia and systemic symptoms (DRESS), and Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN). OBJECTIVE: To carry out a comprehensive analysis on the clinical spectrum and HLA genotype-phenotype correlations in CBZ-induced hypersensitivity reactions. METHODS: We analyzed the clinical information of 194 patients with CBZ hypersensitivity (51 MPE, 23 DRESS, 112 SJS/TEN, and 8 cases with other phenotypes), and 152 CBZ-tolerant controls. All are Han Chinese. We examined the HLA-A/HLA-B genotypes, gene dosage, and drug dosage effects. RESULTS: CBZ-SJS/TEN showed the strongest association with the HLA-B*15:02 allele (Pc=5.8×10(-43); odds ratio (OR) (95% CI)=97.6(42.0-226.8)), in which HLA-B*15:02 was identified in all patients (25/25) with SJS/TEN with >5% body surface area (BSA) skin detachment, but lost its 100% association (85.1%, 74/87) in SJS with <5% BSA detachment. In contrast, HLA-B*40:01 showed negative association with CBZ-induced SJS/TEN ((Pc=8.3×10(-5); OR (95% CI)=0.22(0.1-0.4)). By comparison, CBZ-induced MPE/DRESS had no association with HLA-B*15:02, but linked to HLA-A*31:01 (Pc=2.7×10(-3); OR (95% CI)=6.86(2.4-19.9), and HLA-B*51:01 (Pc=0.01; OR (95% CI)=4.56(2.0-10.5)). No gene dosage or CBZ dosage effects was observed. CONCLUSION: This study reported the different strength of HLA association with CBZ hypersensitivity in Han Chinese. With the increasing application of pharmacogenetic markers, the HLA genotype-phenotype correlations and the results of the test need to be carefully interpreted for CBZ-induced hypersensitivity reactions.

Common risk allele in aromatic antiepileptic-drug induced Stevens-Johnson syndrome and toxic epidermal necrolysis in Han Chinese.

AIMS: Compared with other categories of drugs, such as antibiotics and NSAIDs, antiepileptic therapies are associated with a high incidence of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). We previously reported that carbamazepine (CBZ)-SJS/TEN is strongly associated with the HLA-B*1502 in Han Chinese, which has been confirmed in other Southeast Asian countries where the allele is prevalent. Here, we extend the study of HLA susceptibility to three different antiepileptic drugs, phenytoin (PHT), lamotrigine (LTG) and oxcarbazepine (OXC), which have structure similarity to CBZ. MATERIALS & METHODS: We carried out a case-control association study. We enrolled 26 PHT-, six LTG- and three OXC-induced SJS/TEN patients, 113 PHT-tolerant and 67 LTG-tolerant subjects who were on the drug, respectively, for more than 3 months without the adverse reactions, and 93 normal subjects from the general population. The HLA-A, B, C and DRB1 genotypes were determined. RESULTS: We found that HLA-B*1502 was present in eight out of 26 (30.8%) PHT-SJS/TEN (OR: 5.1; 95% CI: 1.8-15.1; p = 0.0041), two out of six (33%) LTG-SJS (odds ratio [OR]: 5.1; 95% CI: 0.8-33.8; p = 0.1266) and three out of three (100%) OXC-SJS (OR: 80.7; 95% CI: 3.8-1714.4; p = 8.4 x 10(-4)) patients. In addition, HLA-B*1301, Cw*0801 and DRB1*1602 also showed an association with PHT-SJS/TEN (p = 0.0128-0.0281; OR: 3.0-4.3). CONCLUSION: Our results indicate that OXC, PHT and LTG, which possess an aromatic ring just as CBZ does, when causing SJS/TEN, share a common risk allele. Aromatic antiepileptic drugs causing SJS/TEN in HLA-B*1502 carriers may act on a similar pathogenetic mechanism, although other genetic/nongenetic factor(s) may also contribute to the pathomechanism of the disease. We suggest that aromatic antiepileptic drugs, including CBZ, OXC and PHT, should be avoided in the B*1502 carrier and caution should also be exercised for LTG.

Efficacy and safety of levetiracetam (up to 2000 mg/day) in Taiwanese patients with refractory partial seizures: a multicenter, randomized, double-blind, placebo-controlled study.

PURPOSE: To assess the efficacy and safety of adjunctive levetiracetam (LEV) therapy in controlling partial-onset seizures refractory to other antiepileptic drugs (AEDs) in a multicenter study in Taiwanese adults. METHODS: Ninety-four patients aged 16-60 years with refractory partial seizures were randomized to receive LEV (n = 47) or placebo (47) for 14 weeks and composed the intention-to-treat (ITT) population. After the first 2 weeks, LEV patients had their dosage increased from 500 mg twice daily to 1,000 mg twice daily. A 12-week maintenance phase followed, after which patients switched to long-term, open-label LEV therapy or entered a 4-week phase of medication discontinuation. RESULTS: All patients from the ITT population, except one LEV-treated patient with missing seizure-count data, were included in the primary efficacy analysis. The least square mean of logarithmically transformed weekly partial-seizure frequency was significantly lower in the LEV than in the placebo group (0.813 vs. 1.085; p = 0.001). LEV reduced log-transformed weekly partial-seizure frequency by 23.8% (95% confidence interval, 10.4-35.2%) relative to placebo. Significantly more LEV than placebo patients (43.5% vs. 10.6%) experienced a response of a >or=50% decrease from baseline in weekly frequency of partial seizures [odds ratio, 6.5 (95% CI, 2.2-19.3); p < 0.001]. Adverse events were reported in 34 (72.3%) of 47 LEV-treated patients and 32 (68.1%) of 47 placebo patients. The three most common adverse events in the LEV and placebo groups were somnolence (40.4% and 14.9%), dizziness (14.9% and 8.5%), and headache (10.6% and 8.5%), respectively. Only four patients (three LEV-treated patients and one placebo patient) were withdrawn from the study because of adverse events. CONCLUSIONS: Adjunctive LEV therapy,

Medical genetics: a marker for Stevens-Johnson syndrome.

Stevens-Johnson syndrome and the related disease toxic epidermal necrolysis are life-threatening reactions of the skin to particular types of medication. Here we show that there is a strong association in Han Chinese between a genetic marker, the human leukocyte antigen HLA-B*1502, and Stevens-Johnson syndrome induced by carbamazepine, a drug commonly prescribed for the treatment of seizures. It should be possible to exploit this association in a highly reliable test to predict severe adverse reaction, as well as for investigation of the pathogenesis of Stevens-Johnson syndrome.