Napatrupron Koomdee

HLA-B allele and haplotype diversity among Thai patients identified by PCR-SSOP: evidence for high risk of drug-induced hypersensitivity

Background: There are 3 classes of HLA molecules; HLA class I, II and III, of which different classes have different functions. HLA-B gene which belongs to HLA class I play an important role predicting drug hypersensitivity. Materials and Methods: Nine hundred and eighty-six Thai subjects who registered at a pharmacogenomics laboratory were determined for HLA-B genotype using a two-stage sequence-specific oligonucleotide probe system (PCR-SSOP). Results: In this study, HLA-B alleles did not deviate from Hardy-Weinberg equilibrium (P > 0.05). The most common HLA-B alleles observed in this population were HLA-B*46:01 (11.51%), HLA-B*58:01 (8.62%), HLA-B*40:01 (8.22%), HLA-B*15:02 (8.16%) and HLA-B*13:01 (6.95%). This finding revealed that HLA-B allele frequency in the Thai population was consistent with the Chinese population (p > 0.05), however, differed from the Malaysian population (p < 0.05). The top five HLA-B genotypes were HLA-B*40:01/46:01 (2.13%), HLA-B*46:01/46:01 (2.03%), HLA-B*40:01/58:01 (2.03%), HLA-B*46:01/58:01 (1.93%) and HLA-B*15:02/46:01 (1.83%). This study found that 15.92% of Thai subjects carry HLA-B*15:02, which has been associated with carbamazepine-induced severe cutaneous adverse drug reactions (SCARs). Moreover, 16.33% of Thai subjects carry the HLA-B*58:01 allele, which has been associated with allopurinol-induced SCARs. Conclusion: This study demonstrates a high diversity of HLA-B polymorphisms in this Thai population. The high frequency of HLA-B pharmacogenomic markers in the population emphasizes the importance of such screening to predict/avoid drug hypersensitivity.

CYP2C19 polymorphisms in the Thai population and the clinical response to clopidogrel in patients with atherothrombotic-risk factors

Genetic variation in the cytochrome P450 2C19 (CYP2C19) gene has been documented gradually as the determinant conversion and variability in the antiplatelet effect of clopidogrel. The aims of this study were to determine the prevalence of clinically relevant allele variants (CYP2C19*2, CYP2C19*3, and CYP2C19*17) in a Thai study population, and finally determine whether the allele distributes and predicts metabolic phenotypes in clopidogrel treated patients. A total of 1,051 Thai patients participated in this study. Genotypes for CYP2C19 polymorphisms were detected by the microarray-based technique. Furthermore, results of genotyping and platelet aggregation in 96 cardiovascular disease patients on 75 mg clopidogrel maintenance daily dose therapy also were analyzed. Among 1,051 samples, the allele frequencies of CYP2C19 *1/*1, *1/*2, *1/*3, *2/*2, *2/*3, and *1/*17 were found in 428 (40.72%), 369 (35.10%), 72 (6.85%), 77 (7.32%), 59 (5.61%), and 45 (4.30%) of the patients, respectively. Homozygous CYP2C19 *3/*3 was found in one patient (0.10%). Therefore, 40.72% of the patients were predicted as extensive metabolizers, 41.95% as intermediate metabolizers, 13.03% as poor metabolizers, and 4.30% as ultra-rapid metabolizers. Among 96 patients, the frequency of poor metabolizers was significantly higher in the clopidogrel non-responder group than in the responder group (36.0% and 15.5%, respectively, P = 0.03). CYP2C19*1/*17 was observed in responders (n = 2; 2.8%). As a result, CYP2C19 variants were associated with clopidogrel non-responders. However, there is a need for further elucidation of the clinical importance and use of this finding to make firm and cost-effective recommendations for drug treatment in the future.

Association Between Polymorphisms of Dihydrofolate Reductase and Gamma Glutamyl Hydrolase Genes and Toxicity of High Dose Methotrexate in Children with Acute Lymphoblastic Leukemia

Methotrexate (MTX) is an important drug for the treatment of childhood acute lymphoblastic leukemia (ALL). However, related toxicity occurs in many organs which may cause interruption of treatment, morbidity, and mortality. Single nucleotide polymorphisms (SNPs) of dihydrofolate reductase (DHFR) and gamma glutamyl hydrolase (GGH) are known to alter their enzymatic activity and thus affect the metabolism of MTX and influence the effectiveness. Therefore, we hypothesized that genetic variations of DHFR and GGH genes may influence the risk of toxicity after high dose MTX. The study population comprised of 105 children with ALL who were treated according to the modified St Jude Total XV protocol. The patients received 2.5 or 5 g/m2 of MTX for 5 doses during the consolidation phase. Genotyping of DHFR 829C>T and GGH -401C>T was performed using a polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP). The GGH-401CT and TT genotypes were associated with increased risk of leukopenia and thrombocytopenia after high dose MTX (OR 2.97, 95%CI; 1.24-7.13 and OR 4.02, 95%CI; 1.58-10.26). DHFR 829C>T was not associated with toxicity. In conclusion, the GGH -401CT and TT genotypes were found to increase the risk of severe leukopenia and thrombocytopenia after exposure to high dose MTX for childhood ALL therapy.

Dapsone-induced severe cutaneous adverse drug reactions are strongly linked with : 01 allele in the Thai population hla-b : 01 allele in the Thai population*13: 01 allele in the Thai population

Objectives A previous publication in Chinese leprosy patients showed that the HLA-B*13:01 allele is a strong genetic marker for dapsone-induced drug hypersensitivity reactions, however there are no data describing whether HLA-B*13:01 is a valid marker for prediction of dapsone-induced drug hypersensitivity reactions in other ethnicities or nonleprosy patients. The aim of this study is to investigate whether there is an association between HLA genotypes and dapsone-induced severe cutaneous adverse reactions (SCARs) in Thai nonleprosy patients. Patients and methods HLA-B genotypes of 15 patients with dapsone-induced SCARs (11 drug reaction with eosinophilia and systemic symptoms, 4 Stevens–Johnson syndrome/toxic epidermal necrolysis), 29 control patients, and 986 subjects from the general Thai population were determined by the reverse PCR sequence-specific oligonucleotides probe. Results The HLA-B*13:01 allele was significantly associated with dapsone-induced SCARs compared with dapsone-tolerant controls (odds ratio: 54.00, 95% confidence interval: 7.96–366.16, P=0.0001) and the general population (odds ratio: 26.11, 95% confidence interval: 7.27–93.75, P=0.0001). In addition, HLA-B*13:01 associated with dapsone-induced SJS-TEN (OR: 40.50, 95% confidence interval: 2.78-591.01, P=0.0070) and DRESS (OR: 60.75, 95% confidence interval: 7.44-496.18, P=0.0001). Conclusion This study demonstrated an association between HLA-B*13:01 and dapsone-induced SCARs including Stevens–Johnson syndrome/toxic epidermal necrolysis and drug reaction with eosinophilia and systemic symptoms in nonleprosy patients. Moreover, these results suggest that the HLA-B*13:01 allele may be a useful genetic marker for prediction of dapsone-induced SCARs in Thai and Han-Chinese populations.

Polymorphisms of the ApoE (Apolipoprotein E) Gene and Their Influence on Dyslipidemia in HIV-1-Infected Individuals

The purpose of this retrospective case-control study was to investigate the frequency of Apolipoprotein E (ApoE) polymorphisms and their influence on antiretroviral therapy (ART)-induced lipodystrophy or dyslipidemia in HIV-infected Thai patients. The clinical characteristics and frequencies of ApoE genotypes were compared between the case (moderate to severe lipodystrophy, n = 67) and control (absent to mild lipodystrophy, n = 18) groups. The ApoE genotype frequencies among the 85 participants were 2.35% (n = 2) for E2/E2, 20% (n = 17) for E2/E3, 9.41% (n = 8) for E2/E4, 36.47% (n = 31) for E3/E3, 30.59% (n = 26) for E3/E4, and 1.18% (n = 1) for E4/E4. None of the ApoE genotypes showed association with ART-induced lipodystrophy. However, the levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-cholesterol), and ApoB were lower in patients carrying the E2 allele but higher in E4 carriers. Interestingly, the ratios between TC and high-density lipoprotein (TC/HDL cholesterol ratio) and ApoB/ApoA-I ratio were significantly higher in the case group. Patients carrying the E2 allele displayed protective lipid profile, while those carrying E4 appeared to be at higher risk of dyslipidemia. In conclusion, ApoE polymorphisms were not associated with lipodystrophy in patients undergoing antiretroviral therapy but influenced lipid alteration.

Significant Association of HLA-B Alleles and Genotypes in Thai Children with Autism Spectrum Disorders: A Case-Control Study

Autism is a severe neurodevelopmental disorder. Many susceptible causative genes have been identified. Most of the previous reports showed the relationship between the Human Leukocyte Antigen (HLA) gene and etiology of autism. In order to identify HLA-B alleles associated with autism in Thai population, we compared the frequency of HLA-B allele in 364 autistic subjects with 952 normal subjects by using a two-stage sequence-specific oligonucleotide probe system (PCR-SSOP) method based on flow-cytometry technology. HLA-B ⁎ 13:02 (P = 0.019, OR = 2.229), HLA-B ⁎ 38:02 (P = 0.049, OR = 1.628), HLA-B ⁎ 44:03 (P = 0.016, OR = 1.645), and HLA-B ⁎ 56:01 (P = 1.78 × 10−4, OR = 4.927) alleles were significantly increased in autistic subjects compared with normal subjects. Moreover, we found that the HLA-B ⁎ 18:02 (P = 0.016, OR = 0.375) and HLA-B ⁎ 46:12 (P = 0.008, OR = 0.147) alleles were negatively associated with autism when compared to normal controls. Both alleles might have a protective role in disease development. In addition, four HLA-B genotypes of autistic patients had statistically significant relationship with control groups, consisting of HLA-B ⁎ 3905/⁎ 5801 (P = 0.032, OR = 24.697), HLA-B ⁎ 2704/⁎ 5801 (P = 0.022, OR = 6.872), HLA-B ⁎ 3501/⁎ 4403 (P = 0.021, OR = 30.269), and HLA-B ⁎ 1801/⁎ 4402 (P = 0.017, OR = 13.757). This is the first report on HLA-B associated with Thai autism and may serve as a marker for genetic susceptibility to autism in Thai population.

Association of HLA-A and HLA-B Alleles with Lamotrigine-Induced Cutaneous Adverse Drug Reactions in the Thai Population

Background: Lamotrigine (LTG) is commonly used for treatment of epilepsy and bipolar disorder. It is one of the common cause of cutaneous adverse drug reactions (CADR). Clinical symptoms of LTG-induced CADR range from maculopapular exanthema (MPE) to severe cutaneous adverse reactions (SCAR). This study aimed to determine the association of the LTG-induced CADR with human leukocyte antigen (HLA) alleles in Thai patients. Methods: Fifteen patients with LTG-induced CADR [10 MPE; 4 Stevens–Johnson syndrome; and 1 drug reaction with eosinophilia and systemic symptoms] and 50 LTG-tolerant controls were included in the study. HLA-A and HLA-B genotyping was performed using polymerase chain reaction-sequence-specific oligonucleotides probes. Results: The proportion of HLA-A∗02:07 and HLA-B∗15:02 allele carriers were significantly higher in the LTG-induced CADR group than in the tolerant controls [odds ratio (OR): 7.83; 95% confidence interval (CI): 1.60–38.25; P = 0.013, and OR: 4.89; 95% CI: 1.28–18.67; P = 0.014]. In addition, subjects with HLA-A∗33:03, HLA-B∗15:02, and HLA-B∗44:03 were significantly higher in the LTG-induced MPE group than in the tolerant controls (OR: 8.27; 95% CI: 1.83–37.41; P = 0.005, OR: 7.33; 95% CI: 1.63–33.02; P = 0.005; and OR: 10.29; 95% CI: 1.45–72.81; P = 0.029). In contrast to the LTG-induced MPE group, there were no significant differences between HLA alleles and LTG-induced SCAR group. Conclusion: HLA-A∗02:07 and HLA-B∗15:02 were associated with LTG-induced CADR in Thai patients. We also identified an association between HLA-A∗33:03, HLA-B∗15:02, and HLA-B∗44:03 and LTG-induced MPE in this population. These results suggest that these alleles could be useful screening markers for preventing CADR before LTG treatment in Thai patients, but further replication studies with larger sample sizes are needed.

Development and Validation of Voriconazole Concentration by LC-MS-MS: Applied in Clinical Implementation

Voriconazole (VRZ) is a triazole antifungal used for treatment of invasive fungal infection, which is a life‐threatening condition. Therapeutic drug monitoring is recommended for identifying the optimal dose in patients who have hepatic/renal impairment or reduced function of the CYP2C19 metabolizing enzyme.

HLA-B*58:01 allele is strongly associated with allopurinol-induced severe cutaneous adverse reactions in a Thai population

Background Allopurinol has been reported as the most frequent causes of SCARs (severe cutaneous adverse reactions) in Thailand. Recent publications have shown that HLAB*58:01 allele is a strong marker for allopurinol-induced SJS/TEN (Stevens-Johnson syndrome/toxic epidermal necrolysis). The aim of this study was to clarify the association of allopurinol-induced SCARs with the HLA-B*58:01 allele in Thai patients. Method To investigate this relationship, we performed PCR-SSOP (sequence specific oligonucleotide probe) on allopurinoltolerant controls (n=56) and patients affected by allopurinol-induced SCARs (n=14). Among of allopurinol-induced SCARs, including 3 patients with allopurinol-induced DRESS (drug reaction with eosinophilia and systemic symptoms), 9 patients with SJS/TEN and 2 patients with MPE (maculo-papular exanthema) were included. The presence of HLA-B*58:01 allele were genotyped by PCRSSOP method at Laboratory for Pharmacogenomics, Ramathibodi Hospital. Results Of the 14 patients with allopurinol-induced SCARs, 13 (92.8%) patients (3 DRESS, 9 SJS/TEN and one severe MPE) had HLA-B*58:01 while only 6 (10.71%) of the allopurinol-tolerant controls had this allele. The risk of allopurinol-induced SCARs was significantly higher in the patients with HLA-B*58:01 with an OR (odd ratios) of 108.33 (95% CI 11.96-980.82, p<10-6). When compared with normal population, HLA-B*58:01 was associated with a higher risk of SCARs, both DRESS (OR: 80, 95% CI 3.42-372.87) and SJS/TEN (OR: 217.26, 95%CI 12.41-925.35). Conclusion In this study we confirmedthat HLA-B*58:01 allele is strongly associated with allopurinol-induced SCARs in Thai population. Therefore, screening tests for HLAB*58:01 allele in patients who will be treated with allopurinol will be clinically helpful in preventing the risk of developing SCARs.

HLA-B*15:02 genotype associated with hypersensitivity syndrome to lamotrigine in Thai population

Method A total of 133 patients, including 11 patients with lamotrigine-induced hypersensitivity syndrome (MPE; maculo-papular exanthema, SJS; Stevens-Johnson syndrome and TEN; toxic epidermal necrolysis), 9 lamotrigine-tolerant controls and 113 healthy controls were included in this study. HLA-B genotyping was performed. This case-control study was approved by the Ethics Committee of Ramathibodi Hospital.