Publications by authors named "Nuanjun Wichukchinda"

35 Publications

as a potential biomarker for carbamazepine-induced Stevens-Johnson syndrome/toxic epidermal necrolysis in Filipino patients.

Pharmacogenomics 2021 Apr 29. Epub 2021 Apr 29.

Institute of Human Genetics, National Institutes of Health, University of The Philippines Manila, Manila, Philippines.

A case-control study was conducted in Filipino patients to determine the association between HLA alleles and carbamazepine-induced Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN). A retrospective review of medical records and data collection were performed. A total of 10 carbamazepine-induced SJS/TEN cases and 40 tolerant controls were recruited. Genomic DNA extracted from saliva samples was genotyped. Statistical analysis was done. The HLA-B75 serotype (p = 0.003; odds ratio [OR] = 13.8; 95% CI = 2.5-76.8), (p = 0.041; OR = 4.7; 95% CI = 1.1-20.8) and (p = 0.032; OR = 6; 95% CI = 1.2-30.7) were significantly associated with carbamazepine-induced SJS/TEN. The HLA-B75 serotype, or may be used for pharmacogenetic screening prior to prescribing carbamazepine in Filipinos.
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http://dx.doi.org/10.2217/pgs-2020-0191DOI Listing
April 2021

Deficiency of mannose-binding lectin is a risk of Pneumocystis jirovecii pneumonia in a natural history cohort of people living with HIV/AIDS in Northern Thailand.

PLoS One 2020 23;15(12):e0242438. Epub 2020 Dec 23.

Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand.

Background: Mannose-binding lectin (MBL) plays a pivotal role in innate immunity; however, its impact on susceptibility to opportunistic infections (OIs) has not yet been examined in a natural history cohort of people living with HIV/AIDS.

Methods: We used archived samples to analyze the association between MBL expression types and risk of major OIs including Pneumocystis jirovecii pneumonia (PCP), cryptococcosis, talaromycosis, toxoplasmosis, and tuberculosis in a prospective cohort in Northern Thailand conducted from 1 July 2000 to 15 October 2002 before the national antiretroviral treatment programme was launched.

Results: Of 632 patients, PCP was diagnosed in 96 (15.2%) patients, including 45 patients with new episodes during the follow-up period (1006.5 person-years). The total history of PCP was significantly associated with low MBL expression type: high/intermediate (81/587, 13.8%), low (10/33, 30.3%) and deficient (5/12, 41.7%) (p = 0.001), whereas the history of other OIs showed no relation with any MBL expression type. Kaplan-Meier analysis (n = 569; log-rank p = 0.011) and Cox's proportional hazards model revealed that deficient genotype dramatically increased the risk of PCP, which is independent upon sex, age, CD4 count, HIV-1 viral load and hepatitis B and C status (adjusted hazard ratio 7.93, 95% confidence interval 2.19-28.67, p = 0.002).

Conclusions: Deficiency of MBL expression is a strong risk factor determining the incidence of PCP but not other major OIs.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0242438PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7757797PMC
January 2021

The Influence of NAT2 Genotypes on Isoniazid Plasma Concentration of Pulmonary Tuberculosis Patients in Southern Thailand.

Tuberc Respir Dis (Seoul) 2020 Dec 3;83(Supple 1):S55-S62. Epub 2020 Nov 3.

Epidemiology Unit, Faculty of Medicine, Prince of Songkla University, Hat Yai, Thailand.

Background: Isoniazid (INH) is metabolized by polymorphic N-acetyltransferase 2 (NAT2) enzyme, which noticeably alters INH plasma concentration. We aimed to determine the distribution of NAT2 genotype in Thai tuberculosis (TB) patients and correlate their genotype with plasma INH concentrations.

Methods: Blood samples from 55 newly diagnosed pulmonary tuberculosis participants from three hospitals were collected to classify the subject by NAT2 genotype performed by the Multiplex haplotype-specific polymerase chain reaction method. Patients were grouped into three acetylators (fast, intermediate, and slow). On day 14 of tuberculosis treatment, the second blood sample was taken to estimate the peak plasma concentration at 2 hours after oral administration. INH plasma concentration was analyzed by liquid chromatography‒tandem mass spectrometry/mass spectrometry method.

Results: The NAT2 genotype distribution of fast, intermediate, and slow acetylator was 10.9%, 36.4%, and 52.7%, from six, 20, and 29 patients, respectively. The median (interquartile range) of INH plasma concentration at 2 hours post drug administration for these three genotypes were 0.75 (0.69-0.86), 2.56 (2.12-3.97), and 4.25 (3.56-5.50) µg/mL from four, 14, and 12 cases, respectively. The INH plasma concentration at 2 hours after administration was significantly associated with body weight and NAT2 acetylator.

Conclusion: The INH plasma concentration was found lower in fast than intermediate and slow acetylators. Body weight and NAT2 acetylator influenced INH plasma concentrations at 2 hours after drug administration. Therefore, the NAT2 genotype should be known before starting TB treatment to maximize therapeutic outcomes.
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http://dx.doi.org/10.4046/trd.2020.0068DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7837378PMC
December 2020

Haplotype-specific PCR for diplotyping.

Hum Genome Var 2020 11;7:13. Epub 2020 May 11.

1Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand.

N-acetyltransferase 2 (NAT2) is an enzyme that acetylates many kinds of drugs, including the antituberculosis drug isoniazid. The gene is highly diverse across populations. An individual can be classified as having a slow acetylator (SA), an intermediate acetylator (IA), or a rapid acetylator (RA) phenotype based on its two haplotypes (diplotype) of . SA individuals are at a higher risk for isoniazid-induced hepatitis, while the RA phenotype contributes to failure in tuberculosis treatment. Being able to predict individual NAT2 phenotypes is important for dose adjustment of isoniazid. 2 haplotypes are commonly determined via an indirect method of statistical haplotype inference from SNP genotyping. Here, we report a direct haplotyping method using haplotype-specific PCR (HS-PCR) for the 6 most commonly found 2 haplotypes: 2*42*52*62*72*12, and 2*13. Validation of this HS-PCR method via comparison with a sequencing method in 650 Thai DNA samples (107 RA, 279 IA, and 264 SA samples) showed a concordance rate for diplotype calls of 99.23% (645/650 samples). The discordant results in 5 samples were due to 3 rare haplotypes: *5 ( = 3), 2*7 ( = 1), and 2*11 ( = 1). This novel HS-PCR method allows direct 2 diplotyping, enabling the implementation of NAT2 acetylator phenotypes in clinical pharmacogenetic testing.
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http://dx.doi.org/10.1038/s41439-020-0101-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7214404PMC
May 2020

Association of HLA genotypes with phenytoin induced severe cutaneous adverse drug reactions in Thai children.

Epilepsy Res 2020 05 13;162:106321. Epub 2020 Mar 13.

Medical Genetics Center, Medical Life Sciences Institute, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, 11000, Thailand. Electronic address:

Purpose: Phenytoin (PHT) is a common causative drug for severe cutaneous adverse drug reactions (SCARs) in children. SCARs, including drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), are associated with a variation in HLA genotypes. Blood screening for specific HLA allele before PHT prescription would help in the reduction of the incidence of PHT induced SCARs. This study was to investigate the association between variations of HLA genotypes and PHT induced SCARs in Thai children.

Methods: Cases were Thai children aged between 0-18 years diagnosed with SCARs from PHT. Control groups were Thai children of corresponding age who had taken PHT for a least 12 weeks without any hypersensitivity reaction and healthy population controls. Blood samples from both groups were collected for HLA genotyping using a reverse-sequence specific oligonucleotide (SSO) probes method. Carrier rates of HLA alleles were compared between 22 cases (17 DRESS and 5 SJS-TEN), 60 tolerant controls and 649 population controls.

Results: Two HLA alleles includingHLA-B*51:01 and HLA-C*14:02 were significantly associated with PHT induced DRESS (OR 5.83; 95 % CI 1.36-25.00, p = 0.022 and OR 5.85; 95 % CI 1.16-29.35, p = 0.039). HLA-B*38:02 was significantly associated with PHT induced SJS-TEN (OR12.67; 95 % CI 1.50-106.89, p = 0.044). Haplotype analysis demonstrated the association of HLA haplotype A*11:01-B*51:01-C*14:02 and PHT induced DRESS compared to tolerant controls and the healthy population control group (OR 8.92; 95 % CI 1.47-54.02, p = 0.019, and OR 10.2; 95 % CI 3.04-34.21, p = 0.002). HLA haplotype B*38:02-C*07:01 in PHT induced SJS-TEN was significantly higher than those in tolerant controls and the healthy population control group (40 % vs 3.3 % vs 0.3 %; OR 19.33; 95 % CI 1.98-188.59, p = 0.027 and OR 215.67; 95 % CI 22.40-2076.04, p = 0.0003. HLA-B*15:02 was not associated with PHT induced SCARs.

Significance: An association betweenHLA-B*51:01 and HLA-C*14:02 and PHT induced DRESS and HLA-B*38:02 and PHT induced SJS-TEN has been demonstrated in Thai children.
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http://dx.doi.org/10.1016/j.eplepsyres.2020.106321DOI Listing
May 2020

Association of carbamazepine-induced Stevens-Johnson syndrome/toxic epidermal necrolysis with the HLA-B75 serotype or HLA-B*15:21 allele in Filipino patients.

Pharmacogenomics J 2020 06 3;20(3):533-541. Epub 2020 Jan 3.

Institute of Human Genetics, National Institutes of Health, University of the Philippines Manila, Manila, Philippines.

A case-control study was conducted to investigate the association of HLA-A alleles, HLA-B alleles including HLA-B*15:02 and HLA-B75 serotype with carbamazepine-induced SJS/TEN in Filipino patients. A retrospective review of medical records was performed. Pertinent clinical data were collected. Eight (8) carbamazepine-induced SJS/TEN cases and 32 tolerant controls were recruited. Genomic DNA was extracted from the saliva samples and genotyping was performed by employing allele-specific polymerase chain reaction. Data were analyzed using the Fisher's exact test, Mann-Whitney U test, univariate logistic regression, and multivariate logistic regression. Single allele association analysis was done. The strength of association was expressed as odds ratio with 95% confidence interval. Positive predictive value, negative predictive value, sensitivity, and specificity were computed. Of all the alleles tested, the HLA-B75 serotype (p = 0.007, OR = 23.25, 95% CI = 2.33-232.21) and HLA-B*15:21 (p = 0.026, OR = 7.53, 95% CI = 1.27-44.79) were significantly associated with carbamazepine-induced SJS/TEN. The HLA-B75 serotype or HLA-B*15:21 allele may be used as a genetic risk assessment prior to prescription for prevention of carbamazepine-induced SJS/TEN in Filipino patients.
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http://dx.doi.org/10.1038/s41397-019-0143-8DOI Listing
June 2020

Association of HLA genotypes with Beta-lactam antibiotic hypersensitivity in children.

Asian Pac J Allergy Immunol 2019 Apr 23. Epub 2019 Apr 23.

Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand 10400.

Background: Beta-lactam (BL) antibiotics hypersensitivity is common in children. Clinical manifestation of BL hypersensitivity varies from mild to severe cutaneous adverse drug reactions (SCARs).

Objective: To determine the association of HLA genotype and BL hypersensitivity and the prevalence of true drug allergy in patients with history of BL hypersensitivity.

Methods: A case-control study was performed in 117 children with aged 1-18 years. Children with history of non-SCARs BL hypersensitivity were evaluated for true drug hypersensitivity including skin test and drug provocation test. Tolerant control patients were children who could tolerate BL for at least 7 days without hypersensitivity reaction. HLA genotype (HLA-A, HLA-B, HLA-C and HLA-DRB1) were performed in 24 cases and 93 tolerant controls using PCR-SSO (polymerase chain reaction - sequence specific oligonucleotide probes).

Results: There were association of HLA-C*04:06 (OR = 13.14, 95%CI: 1.3-137.71; p = 0.027), and HLA-C*08:01 (OR = 4.83, 95%CI: 1.93-16.70; p = 0.016) with BL hypersensitivity. HLA-B*48:01 was strongly associated with immediate reaction from BL hypersensitivity (OR = 37.4, 95%CI: 1.69-824.59; p = 0.016) while HLA-C*04:06, HLA-C*08:01 and HLA-DRB1*04:06 were associated with delayed reaction (p < 0.05). Among 71 cases who were newly evaluated for BL hypersensitivity, only 7 cases (9.8%) had true BL hypersensitivity.

Conclusions: Less than 10% of children with suspected of BL hypersensitivity have true hypersensitivity. There might be a role of HLA-B, HLA-C and HLA-DRB1 genotype in predicting BL hypersensitivity in Thai children.
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http://dx.doi.org/10.12932/AP-271118-0449DOI Listing
April 2019

Carbamazepine-induced Stevens-Johnson syndrome/toxic epidermal necrolysis overlap in a Filipino with positive HLA-B75 serotype.

BMJ Case Rep 2018 Jul 17;2018. Epub 2018 Jul 17.

Institute of Human Genetics, National Institutes of Health, University of the Philippines Manila, Manila, Philippines.

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are two related mucocutaneous disorders with different severities. Although the incidence is low, SJS and TEN are life-threatening and predominantly drug-induced conditions. There is a strong relationship between the allele and carbamazepine-induced SJS and TEN in different Southeast Asian populations. Here, we report a case of Filipino with SJS/TEN overlap probably induced by carbamazepine. The condition was treated with hydrocortisone followed by prednisone. The allele was not found in this case. The patient tested positive for the HLA-B75 serotype, suggesting that carbamazepine-induced SJS/TEN may be serotype specific. Establishing the genotype before initiation of the drug may be advantageous for some patients and will aid physicians in determining the optimal drug therapy. Prevention of adverse drug reactions (ADR) may be done if pharmacists and other healthcare professionals work as a multidisciplinary ADR team to ensure that safe medication practices are realised.
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http://dx.doi.org/10.1136/bcr-2018-225028DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6058113PMC
July 2018

Impact of HLA Allele-KIR Pairs on Disease Outcome in HIV-Infected Thai Population.

J Acquir Immune Defic Syndr 2018 07;78(3):356-361

National Institute of Health, Ministry of Public Health, Nonthaburi, Thailand.

Background: Class I human leukocyte antigen (HLA) molecules contribute to HIV control through antigen presentation to both cytotoxic T lymphocytes and natural killer cells. Contribution of cytotoxic T lymphocytes to HIV clinical outcome by HLA alleles has been well studied. However, reports about the role of natural killer cells in HIV clinical outcome, particularly, about the effect of HLA-killer immunoglobulin-like receptor (KIR) pairs, remain incomplete.

Methods: The effects of HLA allele-KIR pairs on HIV clinical outcome were statistically analyzed in a Thai cohort of treatment-naive chronically infected population (n = 209).

Results: Five HLA allele-KIR pairs scored significantly in viral load (VL) differences. Among them, opposing effects on VL were identified among subjects expressing KIR2DL2 ligands within the HLA-C1 group: higher VL in individuals expressing HLA-B*46:01+KIR2DL2+ compared with individuals without KIR (HLA-B*46:01+KIR2DL2-) (5.0 vs 4.6 log10 copies/mL, P = 0.02), in HLA-C*01:02+KIR2DL2+ (5.0 vs 4.6 log10 copies/mL; P = 0.02), and lower VL in HLA-C*12:03+KIR2DL2+ (4.3 vs 5.6 log10 copies/mL; P = 0.01). In the longitudinal analysis of a ten-year follow-up, HLA-B*46:01+KIR2DL2+ve subjects also had a higher mortality rate compared with the subjects without that pair, independent of variables including antiretroviral treatment, as well as CD4 T-cell count, sex, and age (adjusted hazard ratio 5.9, P = 0.02).

Conclusion: We identified several HLA allele-KIR pairs associated with clinical outcome differences including opposing effects on VL within 1 HLA group with the same KIR. Among them, HLA-B*46:01 emerged in Southeast Asia about 50,000 years ago and is now the most prevalent HLA-B allele in that area. These findings highlight that each endemic area has unique features of anti-HIV innate immunity that impact clinical outcome.
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http://dx.doi.org/10.1097/QAI.0000000000001676DOI Listing
July 2018

Association of the HLA-B alleles with carbamazepine-induced Stevens-Johnson syndrome/toxic epidermal necrolysis in the Javanese and Sundanese population of Indonesia: the important role of the HLA-B75 serotype.

Pharmacogenomics 2017 Dec 20;18(18):1643-1648. Epub 2017 Oct 20.

College of Pharmacy, University of Florida, Gainesville, FL 32603, USA.

Carbamazepine (CBZ) is a common cause of life-threatening cutaneous adverse drug reactions such as Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Previous studies have reported a strong association between the HLA genotype and CBZ-induced SJS/TEN. We investigated the association between the HLA genotype and CBZ-induced SJS/TEN in Javanese and Sundanese patients in Indonesia. Nine unrelated patients with CBZ-induced SJS/TEN and 236 healthy Javanese and Sundanese controls were genotyped for HLA-B and their allele frequencies were compared. The HLA-B*15:02 allele was found in 66.7% of the patients with CBZ-induced SJS/TEN, but only in 29.4% of tolerant control (p = 0.029; odds ratio [OR]: 6.5; 95% CI: 1.2-33.57) and 22.9% of healthy controls (p = 0.0021; OR: 6.78; 95% CI: 1.96-23.38). These findings support the involvement of HLA-B*15:02 in CBZ-induced SJS/TEN reported in other Asian populations. Interestingly, we also observed the presence of the HLA-B*15:21 allele. HLA-B*15:02 and HLA-B*15:21 are members of the HLA-B75 serotype, for which a greater frequency was observed in CBZ-induced SJS/TEN (vs tolerant control [p = 0.0078; OR: 12; 95% CI: 1.90-75.72] and vs normal control [p = 0.0018; OR: 8.56; 95% CI: 1.83-40]). Our findings suggest that screening for the HLA-B75 serotype can predict the risk of CBZ-induced SJS/TEN more accurately than screening for a specific allele.
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http://dx.doi.org/10.2217/pgs-2017-0103DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5753619PMC
December 2017

Pathogen lineage-based genome-wide association study identified CD53 as susceptible locus in tuberculosis.

J Hum Genet 2017 Dec 7;62(12):1015-1022. Epub 2017 Sep 7.

Medical Genetics Center, Medical Life Sciences Institute, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand.

Tuberculosis (TB) is known to be affected by host genetic factors. We reported a specific genetic risk factor through a genome-wide association study (GWAS) that focused on young age onset TB. In this study, we further focused on the heterogeneity of Mycobacterium tuberculosis (M. tb) lineages and assessed its possible interaction with age at onset on host genetic factors. We identified the pathogen lineage in 686 Thai TB cases and GWAS stratified by both infected pathogen lineage information and age at onset revealed a genome-wide significant association of one single-nucleotide polymorphism (SNP) on chromosome 1p13, which was specifically associated with non-Beijing lineage-infected old age onset cases (P=2.54E-08, OR=1.74 (95% CI=1.43-2.12)), when we compared them to the population-matched healthy controls. This SNP locates near the CD53 gene, which encodes a leukocyte surface glycoprotein. Interestingly, the expression of CD53 was also correlated with the patients' active TB status. This is the first report of a pathogen lineage-based genome-wide association study. The results suggested that host genetic risk in TB is depended upon the pathogen genetic background and demonstrate the importance of analyzing the interaction between host and pathogen genomes in TB.
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http://dx.doi.org/10.1038/jhg.2017.82DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5709719PMC
December 2017

Genome-wide association study of neovascular age-related macular degeneration in the Thai population.

J Hum Genet 2017 Nov 13;62(11):957-962. Epub 2017 Jul 13.

Medical Genetics Center, Medical Life Sciences Institute, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand.

We performed a genome-wide association study on 377 cases of neovascular age-related macular degeneration (AMD) and 1074 controls to determine the association of previously reported genetic variants associated with neovascular AMD in the Thai population. All patients were of Thai ancestry. We confirmed the association of age-related maculopathy susceptibility 2 (ARMS2) rs10490924 (P=7.38 × 10), HTRA1 rs11200638 (P=5.47 × 10) and complement factor H gene (CFH) rs800292 (P=2.53 × 10) with neovascular AMD, all loci passing the genome-wide significance level (P<5.22 × 10). We also found association of the previously reported CFH rs10737680 (P=1.76 × 10) locus in the discovery sample. Two loci not previously reported to be associated with neovascular AMD were selected for replication in 222 cases and 623 controls. The loci included LINCO1317 rs6733379 and rs2384550 on chromosome 12. LINCO1317 rs6733379 (P=3.85 × 10) remained significantly associated with neovascular AMD after replication. In conclusion, we confirm that ARMS2, HTRA1 and CFH variants are associated with neovascular AMD in the Thai population. Findings from this study also suggest that variants contributing to the susceptibility of neovascular AMD in the Thai population are mostly similar to other Asians with additional local genetic risks that may specifically be identified in Thai population.
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http://dx.doi.org/10.1038/jhg.2017.72DOI Listing
November 2017

Association of HLA genotypes with phenobarbital hypersensitivity in children.

Epilepsia 2016 Oct 24;57(10):1610-1616. Epub 2016 Aug 24.

Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.

Objective: Phenobarbital hypersensitivity is one of the common drug hypersensitivity syndromes in children. Clinical symptoms of phenobarbital hypersensitivity vary from maculopapular rashes (MPs) to severe cutaneous adverse drug reactions (SCARs) including drug reactions with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN). Drug hypersensitivity has been demonstrated to be associated with variations in the HLA genotypes. This study was to investigate the association between the variations of HLA genotypes and phenobarbital hypersensitivity in Thai children.

Methods: The cases were Thai children, between 0 and 18 years of age, who were diagnosed with phenobarbital hypersensitivity, which included SCARs and MPs. The control patients were Thai children of a corresponding age who had taken phenobarbital for at least 12 weeks without any hypersensitivity reaction. Blood samples were collected for HLA genotyping by using a reverse-sequence-specific oligonucleotide (SSO) probes method. The carrier rates of HLA alleles were compared between 47 cases (27 SCARs and 20 MPs) and 54 controls.

Results: The carrier rates of HLA-A*01:01 and HLA-B*13:01 were significantly higher in the phenobarbital-induced SCARs than in the tolerant controls (18.5% vs. 1.85%, p = 0.01, odds ratio [OR] 11.66, 95% confidence interval [CI] 1.21-578.19; 37.04% vs. 11.11%, p = 0.009, OR 4.60, 95%CI 1.29-17.98). There was a trend of a higher carrier rate of HLA-C*06:02 in the phenobarbital-induced SCARs when compared with those in the tolerant controls (29.63% vs. 11.11%, p = 0.059, OR 3.31, 95% CI 0.88-13.31). In contrast to the phenobarbital-induced SCARs, only the HLA-A*01:01 carrier rate in the phenobarbital-induced MPs was significantly higher than those in the tolerant controls (20% vs. 1.85%, p = 0.017, OR 12.69, 95% CI 1.15-661.62).

Significance: An association between phenobarbital hypersensitivity and HLA-A*01:01 and HLA-B*13:01 has been demonstrated in Thai children.
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http://dx.doi.org/10.1111/epi.13509DOI Listing
October 2016

Association of BAK1 single nucleotide polymorphism with a risk for dengue hemorrhagic fever.

BMC Med Genet 2016 07 11;17(1):43. Epub 2016 Jul 11.

Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan.

Background: Dengue hemorrhagic fever (DHF) is a severe life-threatening form of dengue infection. Low platelet count is one of the characteristic clinical manifestations in patients with severe dengue. However, little is known about genetic factors in the host that cause low platelet count in patients with dengue.

Methods: A previous genome-wide association study of hematological and biochemical traits identified single nucleotide polymorphisms (SNPs) associated with low platelet count in healthy subjects. To examine the possible association of these SNPs with DHF, 918 Thai patients with dengue [509 patients with DHF and 409 with dengue fever (DF)] were genotyped for five SNPs: rs5745568 in BAK1, rs6141 in THPO, rs6065 in GP1BA, rs739496 in SH2B3, and rs385893 in RCL1. In addition, rs4804803 in CD209, that has been reported to be associated with dengue infection, was also genotyped to examine if rs4804803 affects the association detected in this study.

Results: The allele frequencies of each SNP were compared between the DHF and DF groups. Among the five SNPs, the G allele of rs5745568 in BAK1 was significantly associated with a risk for DHF [P = 0.006 and crude odd ratio (95 % confidence interval) = 1.32 (1.09-1.60)]. The association of this allele with DHF was also significant in a logistic regression analysis adjusted for age, sex, hospital (i.e., geographic region), immune status (i.e., primary or secondary infection), and virus serotype [P = 0.016 and adjusted odd ratio (95 % confidence interval) = 1.29 (1.05-1.58)]. The result was not influenced by rs4804803 [P = 0.0167 and adjusted OR (95 % CI) = 1.29 (1.05-1.58)]. No other SNPs including rs4804803 showed significant association.

Conclusions: The low-level constitutive production of platelets caused by the G allele of rs5745568 seems to increase the risk of bleeding in dengue infection. Our results suggest that BCL-2 homologous antagonist/killer (BAK) protein, encoded by BAK1, plays a crucial role in the pathogenesis of DHF.
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http://dx.doi.org/10.1186/s12881-016-0305-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4940700PMC
July 2016

Associations between HLA class I and cytochrome P450 2C9 genetic polymorphisms and phenytoin-related severe cutaneous adverse reactions in a Thai population.

Pharmacogenet Genomics 2016 May;26(5):225-34

aDepartment of Pharmacology bPharmacy Unit cDepartment of Medicine, Faculty of Medicine dIntegrated Epilepsy Research Group eFaculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen fDepartment of Pathology, Division of Pharmacogenomics and Personalized Medicine gLaboratory for Pharmacogenomics, Somdech Phra Debaratana Medical Center (SDMC) hDepartment of Medicine, Division of Allergy Immunology and Rheumatology, Faculty of Medicine Ramathibodi Hospital, Mahidol University iPharmacy Unit, Police General Hospital, Bangkok jPharmacy Unit, Udon Thani Hospital, Udon Thani kDepartment of Medicine, Faculty of Medicine, Thammasat University, Pathumthani lMedical Genetics Center, Medical Life Sciences Institute, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand.

Background: Phenytoin is one of the most common causative drugs of several types of severe cutaneous adverse reactions (SCAR) such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reactions with eosinophilia and systemic symptoms (DRESS). Genetic polymorphisms of the human leukocyte antigens (HLA) and cytochromes P450 (CYP) have been proposed as key elements for the susceptibility to phenytoin-related SCAR in certain ethnicities. This study investigated the associations between the genetic polymorphisms of HLA class I and CYP2C9 and phenytoin-related SCAR in a Thai population.

Materials And Methods: Sixty phenytoin-related SCAR (i.e. 39 SJS/TEN and 21 DRESS) and 92 phenytoin-tolerant patients were enrolled in the study. The genotypes of HLA class I and CYP2C9 were determined.

Results: Six HLA alleles including HLA-A*33:03, HLA-B*38:02, HLA-B*51:01, HLA-B*56:02, HLA-B*58:01, and HLA-C*14:02 were significantly associated with phenytoin-related SJS/TEN, whereas only the HLA-B*51:01 was significantly associated with phenytoin-related DRESS. The odds ratios of phenytoin-related SJS/TEN in the patients who carried one of these alleles ranged from 4- to 10-fold. The frequencies of patients who carried the HLA-B*15:02 in the SJS/TEN (12.82%) or the DRESS (9.52%) groups were not significantly different from that of the controls (14.13%). The higher risk of phenytoin-related SJS/TEN was observed in the patients with CYP2C9*3 (odds ratio=4.30, 95% confidence interval=1.41-13.09, P<0.05).

Conclusion: Neither SJS/TEN nor DRESS caused by phenytoin was significantly associated with the HLA-B*15:02. The CYP2C9*3 variant was significantly associated with phenytoin-related SJS/TEN, but not DRESS. Certain alleles of HLA, particularly HLA-B*56:02, were significantly associated with phenytoin-related SCAR in the study population.
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http://dx.doi.org/10.1097/FPC.0000000000000211DOI Listing
May 2016

Comparison of genetic variation in drug ADME-related genes in Thais with Caucasian, African and Asian HapMap populations.

J Hum Genet 2016 Feb 1;61(2):119-27. Epub 2015 Oct 1.

Department of Pathology, Faculty of Medicine, Ramathibodhi Hospital, Mahidol University, Bangkok, Thailand.

The objectives of this study are to investigate allele frequencies of drug absorption, distribution, metabolism and elimination (ADME)-related genes in the Thai population and to compare these genes to HapMap populations including Caucasians (CEU), Africans (YRI) and Asians (CHB/JPT). Genetic variations of drug ADME-related genes in 190 Thais were investigated using drug metabolizing enzymes and transporters (DMET) plus genotyping system. We examined 1936 single nucleotide polymorphisms (SNPs) of 225 genes that have documented functional and clinical significances in phase I and phase II drug metabolism enzymes, drug transporters and other genes involved in ADME processes. Distributions of genotyping data from Thai were compared with other HapMap populations including Caucasian, African and Asian populations. The analysis demonstrated 43 SNPs with statistical significance comparing among five populations. However, only 26 SNPs showed statistical significance in pair-wise comparisons between Thai versus CEU and Thai versus CHB/JPT. These 26 SNPs belong to 13 groups of drug ADME-related genes which are CYP2A6, CYP3A5, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, VKORC1, COMT, NAT2, TPMT, UGT1A1 and SLCO1B1. These genes demonstrated clinical significances as previously observed in many studies. The results could explain clinical variability in pharmacokinetics and pharmacodynamics of drugs in Thais based on genetic variations in drug ADME-related gene emphasized in this article.
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http://dx.doi.org/10.1038/jhg.2015.115DOI Listing
February 2016

The effect of KIR2D-HLA-C receptor-ligand interactions on clinical outcome in a HIV-1 CRF01_AE-infected Thai population.

AIDS 2015 Aug;29(13):1607-15

aDepartment of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan bDepartment of Paediatrics, University of Oxford, Oxford, UK cThai National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Nonthaburi dDay Care Centre, Lampang Hospital, Lampang, Thailand eNagasaki University Global COE Program, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan.

Objective: Class I human leukocyte antigen (HLA) alleles interact with both cytotoxic T lymphocytes through their T-cell receptors, and natural killer cells through their killer immunoglobulin-like receptors (KIRs). Compared with the reported protective effect of KIR3DL1/S1-HLA-Bw4 interactions in HIV-infected patients, the effect of KIR2D-HLA-C combinations on HIV control remains unclear. Here, we investigate the effect of KIR2D-HLA-C combinations on HIV disease progression.

Design: We performed a cross-sectional and longitudinal analysis of a Thai HIV cohort.

Methods: Two hundred and nine HIV-1 CRF01_AE-infected, treatment-naive Thai patients (CD4 T-cell counts of >200/μl) and 104 exposed seronegatives were studied. The effect of KIR-HLA receptor-ligand combinations on viral transmission and survival rate was statistically analyzed.

Results: We found the following results: higher frequency of patients expressing both KIR2DL3 and HLA-C1 among infected patients compared with exposed seronegative (odds ratio 4.8, P = 0.004), higher viral load in patients expressing HLA-C1 with KIR2DL3 compared with those without this receptor-ligand combination (median 4.8 vs. 4.2 log copies/ml, P = 0.033), higher numbers of KIR2DL3-HLA-C1 interactions was associated with a higher viral load (β = 0.13, P = 0.039 by linear regression model), and higher mortality rate in carriers of the KIR2DL3-HLA-C1 combination (adjusted hazard ratio 1.9, P = 0.012 by Cox hazard model).

Conclusion: We have identified a deleterious effect of the KIR2DL3-HLA-C1 receptor-ligand combination on HIV clinical outcomes in a Thai cohort. Further investigation into mechanisms underlying this susceptibility may aid the understanding of the role of natural killer cells in HIV disease control and pathogenesis.
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http://dx.doi.org/10.1097/QAD.0000000000000747DOI Listing
August 2015

Candidate HLA genes for prediction of co-trimoxazole-induced severe cutaneous reactions.

Pharmacogenet Genomics 2015 Aug;25(8):402-11

aDepartment of Pharmacology bPharmacy Unit cDepartment of Medicine, Faculty of Medicine dFaculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen eMedical Genetics Center, Medical Life Science Institute, Department of Medical Sciences, Ministry of Public Health fHealth Product Vigilance Center, Food and Drug Administration, Ministry of Public Health, Nonthaburi gPharmacy Unit hDepartment of Medicine, Udon Thani Hospital, Udon Thani iBuddhachinaraj Hospital, Phitsanulok jLampang Hospital, Lampang kRayong Hospital, Rayong lSongkhla Hospital, Songkhla mChiangraiprachanukroh Hospital, Chiangrai, Thailand.

Background: Co-trimoxazole is a sulfonamide-containing antibiotic that is effective in the treatment of several infections and for prophylaxis of Pneumocystis jiroveci pneumonia. This drug has been reported as a common culprit drug for the Stevens-Johnson syndrome (SJS) and for toxic epidermal necrolysis (TEN). Human leukocyte antigens (HLAs) play a key role in the immunopathogenesis of severe cutaneous reactions induced by several drugs. This study investigated the association between the HLA class I and HLA-DRB1 polymorphisms and co-trimoxazole-induced SJS/TEN in a Thai population.

Methods: Forty-three patients with co-trimoxazole-induced SJS/TEN and 91 co-trimoxazole-tolerant patients were enrolled in the study. HLA class I and HLA-DRB1 were genotyped using the reverse sequence-specific oligonucleotide probe method.

Results: The frequencies of three alleles of HLA, namely HLA-B*15:02, HLA-C*06:02, and HLA-C*08:01, were significantly higher in the co-trimoxazole-induced SJS/TEN group compared with controls. The risks for co-trimoxazole-induced SJS/TEN in patients with the HLA-B*15:02, HLA-C*06:02, or HLA-C*08:01 allele were about 3-11-fold higher when compared with those who did not carry one of these alleles. Individuals who carried the HLA-B*15:02-C*08:01 haplotype had a 14-fold higher risk for co-trimoxazole-induced SJS/TEN.

Conclusion: Evidence of associations between co-trimoxazole-induced SJS/TEN and HLA alleles including HLA-B*15:02, HLA-C*06:02, and HLA-C*08:01 were found in the study population. These findings may suggest that apart from the HLA molecules, other molecules involved in the molecular pathogenesis of these severe cutaneous adverse drug reactions may play an important role in the susceptibility of individuals to SJS/TEN caused by co-trimoxazole.
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http://dx.doi.org/10.1097/FPC.0000000000000153DOI Listing
August 2015

Association analysis of CYP2C9*3 and phenytoin-induced severe cutaneous adverse reactions (SCARs) in Thai epilepsy children.

J Hum Genet 2015 Aug 21;60(8):413-7. Epub 2015 May 21.

Medical Genetic Centre, Medical Life Science Institute, Department of Medical Science, Ministry of Public Health, Nontaburi, Thailand.

CYP2C9 is the key enzyme in aromatic antiepileptic drugs (AEDs) metabolism. CYP2C9*3 is a loss of function polymorphism. This study was designed to investigate genetic association between CYP2C9*3 and aromatic AED-induced severe cutaneous adverse reactions (SCARs) in Thai children. The 37 aromatic AED-induced SCARs patients (20 phenobarbital and 17 phenytoin) and 35 tolerances (19 phenobarbital and 16 phenytoin) were enrolled. CYP2C9*3 was genotyped by allele-specific PCRs. The association between CYP2C9*3 with phenytoin-induced SCARs and phenobarbital-induced SCARs were analyzed in comparison with tolerances and healthy samples. Significant association between phenytoin-induced SCARs and CYP2C9*3 was discovered (odds ratio=14.52; 95% confidence interval (CI)=1.18-∞, P-value=0.044). CYP2C9*3 was not associated with phenobarbital-induced SCARs. This study is the first report of CYP2C9*3 association to phenytoin-induced SCARs in Thai epileptic children. The CYP2C9*3 is a reasonable predictive genetic marker to anticipate SCARs from phenytoin.
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http://dx.doi.org/10.1038/jhg.2015.47DOI Listing
August 2015

Incidence and predictors of regimen-modification from first-line antiretroviral therapy in Thailand: a cohort study.

BMC Infect Dis 2014 Oct 30;14:565. Epub 2014 Oct 30.

Food and Drug Administration, Ministry of Public Health, 88/7 Tiwanon road, Ampur Muang, Nonthaburi, 11000, Thailand.

Background: Antiretroviral therapy markedly reduced mortality in HIV-infected individuals. However, in the previous studies, up to 50% of patients are compelled to modify their regimen in middle and low-income countries where salvage drug is still limited. This cohort study aimed to investigate the incidence and predictors of regimen modification from the first-line antiretroviral regimen in northern Thailand.

Methods: All HIV-infected patients starting antiretroviral therapy (ART) with generic drug (GPOvir®; stavudine, lamivudine and nevirapine) at a governmental hospital in northern Thailand from 2002 to 2007 were recruited. Baseline characteristics and detailed information of regimen modification until the end of 2010 were ascertained from cohort database and medical charts. As a potential genetic predictor of regimen modification, HLA B allele was determined by bead-based array hybridization (WAKFlow® HLA typing kit). We investigated predictors of the regimen modification using Cox's proportional hazard models.

Results: Of 979 patients, 914 were eligible for the analysis. The observed events of regimen modification was 377, corresponding to an incidence 13.8/100 person-year-observation (95% CI:12.5-15.3) over 2,728 person years (PY) follow up. The main reasons for regimen modification were adverse effects (73.5%), especially lipodystrophy (63.2%) followed by rash (17.7%). Sixty three patients (17.1%) changed the regimen due to treatment failure. 2% and 19% of patients had HLA-B*35:05 and B*4001, respectively. HLA-B*35:05 was independently associated with rash-related regimen modification (aHR 7.73, 95% CI:3.16-18.9) while female gender was associated with lipodystrophy (aHR 2.11, 95% CI:1.51-2.95). Female gender (aHR 0.54, 95% CI: 0.30-0.96), elder age (aHR 0.56, 95% CI: 0.32-0.99) and having HLA-B*40:01 (aHR 0.29, 95% CI: 0.10-0.82) were protective for treatment failure related modification.

Conclusion: HLA-B*35:05 and female gender were strong predictors of regimen modification due to rash and lipodystrophy, respectively. Female gender, elder age, and having HLA-B*40:01 had protective effects on treatment failure-related regimen modification. This study provides further information of regimen modification for future tailored ART in Asia.
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http://dx.doi.org/10.1186/s12879-014-0565-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4226857PMC
October 2014

A replication study confirms the association of GWAS-identified SNPs at MICB and PLCE1 in Thai patients with dengue shock syndrome.

BMC Med Genet 2014 May 17;15:58. Epub 2014 May 17.

Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.

Background: Dengue shock syndrome (DSS), a severe life-threatening form of dengue infection, mostly occurs in children. A recent genome wide association study (GWAS) identified two SNPs, rs3132468 of major histocompatibility complex class I polypeptide-related sequence B (MICB) and rs3765524 of phospholipase C, epsilon 1 (PLCE1), associated with DSS in Vietnamese children. In this study, to examine whether an identical association is found in a different population, the association of these two SNPs with DSS was assessed in Thai children with dengue.

Methods: The rs3132468 and rs3765524 SNPs were genotyped in 917 Thai children with dengue: 76 patients with DSS and 841 patients with non-DSS. The allele frequencies were compared between DSS and non-DSS groups by one-sided Fisher's exact test. The association of rs3132468 and rs3765524 with the mRNA expression levels of MICB and PLCE1 were assessed in EBV-transformed lymphoblastoid cell lines.

Results: The reported DSS-risk alleles were significantly associated with DSS in Thai patients with dengue (one-sided P = 0.0213 and odds ratio [OR] = 1.58 for rs3132468-C and one-sided P = 0.0252 and OR = 1.49 for rs3765524-C). The rs3132468-C allele showed a significant association with lower mRNA level of MICB (P = 0.0267), whereas the rs3765524-C allele did not. These results imply that the MICB molecule may play an important role in the prevention of DSS in dengue infection.

Conclusions: Together with previous association studies, we conclude that rs3132468-C at MICB and rs3765524-C at PLCE1 confer risk of DSS in Southeast Asians.
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http://dx.doi.org/10.1186/1471-2350-15-58DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4030448PMC
May 2014

HLA-B*35: 05 is a protective allele with a unique structure among HIV-1 CRF01_AE-infected Thais, in whom the B*57 frequency is low.

AIDS 2014 Apr;28(7):959-67

Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Sakamoto, Nagasaki City, Nagasaki, Japan.

Objective: To identify protective human leukocyte antigen (HLA) alleles in an HIV-infected south-east Asian population, in whom HLA-B*57 prevalence is lower than other ethnic groups, and HIV-1 CRF01_AE is the dominant circulating subtype.

Design: Cross-sectional study of Thai patients with chronic HIV infection.

Methods: Five hundred and fifty-seven HIV-1 CRF01_AE-infected Thais were recruited. Their HLA type and viral load were determined to statistically analyze the association of each allele in viral control. In-silico molecular dynamics was also used to evaluate the effect of HLA structure variants on epitope binding.

Results: HLA-B*35:05 was identified as the most protective allele (P=0.003, q=0.17), along with HLA-B*57:01 (P=0.044, q=0.31). Structurally, HLA-B*35:05 belonged to the HLA-B*35-PY group of HLA-B*35 alleles; however, unlike the other HLA-B*35 alleles that carry Arg (R) at residue 97, it has unique sequences at T94, L95, and S97, located within the peptide-binding groove. Analysis of the three-dimensional HLA structure and molecular dynamics indicates that S97 in HLA-B*35:05 leads to less flexibility in the groove, and shorter distances between the α-helixes compared with the disease-susceptible HLA-B*35-PY allele, HLA-B*35:01.

Conclusion: These data indicate the existence of a protective effect of HLA-B*57 across ethnic groups and highlight HLA-B*35:05 as an allele uniquely protective in subtype CRF01_AE-infected Thais. The divergence of HLA-B*35:05 from conventional HLA-B*35-PY structural sequences at the peptide-binding groove is consistent with previous studies that have identified HLA residue 97 as strongly influential in shaping HLA impact on immune control of HIV, and that a more restricted peptide-binding motif may be associated with improved control.
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http://dx.doi.org/10.1097/QAD.0000000000000206DOI Listing
April 2014

Influence of ABCB-1 C3435T polymorphisms on plasma nevirapine and efavirenz levels and their effects on virologic and immunological outcomes in HIV/TB co-infected Thai adults under anti-retroviral therapy.

Southeast Asian J Trop Med Public Health 2012 Jan;43(1):78-88

Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.

ATP-binding cassette, sub-family B (encoded by ABCB-1 or MDR-1) has an important role in cellular export of antiretroviral agents. A previous study showed that ABCB-1 C3435T polymorphism affects plasma efavirenz and nelfinavir concentrations and rate of CD4+ T cell recovery after starting antiretroviral treatment (ART). The present study examined the influence of ABCB-1 polymorphisms on plasma nevirapine and efavirenz levels when co-administered with rifampicin in 124 HIV/TB patients who received nevirapine- (400 mg/day) (n = 59) and efavirenz- (600 mg/day) (n = 65) based ART. ABCB-1 C3435T polymorphisms were genotyped using real-time PCR. CD4 T cell counts and HIV-1 viral RNA were evaluated in response to ART. The frequencies of CC, CT and TT genotypes of ABCB-1 C3435T polymorphism were 34% (n = 42), 55% (n = 68) and 12% (n = 14), respectively. Contrary to the previous report, no association was found among these genotypes and plasma drug concentrations at weeks 6 and 12 of ART and after rifampicin discontinuation. We also observed no differences in CD4+ T cell recovery rate among different ABCB-1 C3435T genotypes. In nevirapine group, however, all the patients with CT genotype achieved HIV-1 RNA levels of < 50 copies/ml, while 67% of those with TT and 95% with CC genotypes achieved < 50 copies/ml (p = 0.040). These data suggested that ABCB-1 C3435T polymorphisms do not affect plasma nevirapine and efavirenz concentrations in HIV/TB co-infected Thai patients or their immunological outcome, but had an effect on virologic outcome in the nevirapine-treated group.
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January 2012

Genome-wide association studies of tuberculosis in Asians identify distinct at-risk locus for young tuberculosis.

J Hum Genet 2012 Jun 3;57(6):363-7. Epub 2012 May 3.

Medical Genetics Section, National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand.

Tuberculosis (TB) is one of the most devastating chronic infectious diseases, but the role of host genetics in disease development after infection in this disease remains unidentified. Genome-wide association studies (GWASs) in Thais and Japanese were carried out and separately analyzed, attempted replication, then, combined by meta-analysis were not yielding any convincing association evidences; these results suggested that moderate to high effect-size genetic risks are not existed for TB per se. Because of failure in replication attempt of the top 50 single-nucleotide polymorphisms (SNPs) identified form meta-analysis data, we empirically split TB cases into young TB case/control data sets (GWAS-T(young)=137/295 and GWAS-J(young)=60/249) and old TB case/control data sets (GWAS-T(old)=300/295 and GWAS-J(old)=123/685), re-analyzed GWAS based on age-stratified data and replicated the significant findings in two independent replication samples (young TB; Rep-T(young)=155/249, Rep-J(young)=41/462 and old TB; Rep-T(old)=212/187, Rep-J(old)=71/619). GWAS and replication studies conducted in young TB identified at-risk locus in 20q12. Although the locus is located in inter-genic region, the nearest genes (HSPEP1-MAFB) from this locus are promising candidates for TB susceptibility. This locus was also associated with anti-TNF responsiveness, drug with increased susceptibility for TB. Moreover, eight SNPs in an old TB meta-analysis and six SNPs in young TB meta-analysis provided replication evidences but did not survive genome-wide significance.These findings suggest that host genetic risks for TB are affected by age at onset of TB, and this approach may accelerate the identification of the major host factors that affect TB in human populations.
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http://dx.doi.org/10.1038/jhg.2012.35DOI Listing
June 2012

Unique CRF01_AE Gag CTL epitopes associated with lower HIV-viral load and delayed disease progression in a cohort of HIV-infected Thais.

PLoS One 2011 3;6(8):e22680. Epub 2011 Aug 3.

Department of Clinical Medicine, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan.

Cytotoxic T Lymphocytes (CTLs) play a central role in controlling HIV-replication. Although numerous CTL epitopes have been described, most are in subtype B or C infection. Little is known about CTL responses in CRF01_AE infection. Gag CTL responses were investigated in a cohort of 137 treatment-naïve HIV-1 infected Thai patients with high CD4+ T cell counts, using gIFN Enzyme-Linked Immunospot (ELISpot) assays with 15-mer overlapping peptides (OLPs) derived from locally dominant CRF01_AE Gag sequences. 44 OLPs were recognized in 112 (81.8%) individuals. Both the breadth and magnitude of the CTL response, particularly against the p24 region, positively correlated with CD4+ T cell count and inversely correlated with HIV viral load. The breadth of OLP response was also associated with slower progression to antiretroviral therapy initiation. Statistical analysis and single peptide ELISpot assay identified at least 17 significant associations between reactive OLP and HLA in 12 OLP regions; 6 OLP-HLA associations (35.3%) were not compatible with previously reported CTL epitopes, suggesting that these contained new CTL Gag epitopes. A substantial proportion of CTL epitopes in CRF01_AE infection differ from subtype B or C. However, the pattern of protective CTL responses is similar; Gag CTL responses, particularly against p24, control viral replication and slow clinical progression.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0022680PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3149616PMC
December 2011

HLA-associated immune pressure on Gag protein in CRF01_AE-infected individuals and its association with plasma viral load.

PLoS One 2010 Jun 17;5(6):e11179. Epub 2010 Jun 17.

Department of Microbiology, Faculty of Science, Mahidol University, Bangkok, Thailand.

Background: The human leukocyte antigen (HLA)-restricted cytotoxic T-lymphocyte (CTL) immune response is one of the major factors determining the genetic diversity of human immunodeficiency virus (HIV). There are few population-based analyses of the amino acid variations associated with the host HLA type and their clinical relevance for the Asian population. Here, we identified HLA-associated polymorphisms in the HIV-1 CRF01_AE Gag protein in infected married couples, and examined the consequences of these HLA-selected mutations after transmission to HLA-unmatched recipients.

Methodology/principal Findings: One hundred sixteen HIV-1-infected couples were recruited at a government hospital in northern Thailand. The 1.7-kb gag gene was amplified and directly sequenced. We identified 56 associations between amino acid variations in Gag and HLA alleles. Of those amino acid variations, 35 (62.5%) were located within or adjacent to regions reported to be HIV-specific CTL epitopes restricted by the relevant HLA. Interestingly, a significant number of HLA-associated amino acid variations appear to be unique to the CRF01_AE-infected Thai population. Variations in the capsid protein (p24) had the strongest associations with the viral load and CD4 cell count. The mutation and reversion rates after transmission to a host with a different HLA environment varied considerably. The p24 T242N variant escape from B57/58 CTL had a significant impact on the HIV-1 viral load of CRF01_AE-infected patients.

Conclusions/significance: HLA-associated amino acid mutations and the CTL selection pressures on the p24 antigen appear to have the most significant impact on HIV replication in a CRF01_AE-infected Asian population. HLA-associated mutations with a low reversion rate accumulated as a footprint in this Thai population. The novel HLA-associated mutations identified in this study encourage us to acquire more extensive information about the viral dynamics of HLA-associated amino acid polymorphisms in a given population as effective CTL vaccine targets.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0011179PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2887364PMC
June 2010

TIM1 haplotype may control the disease progression to AIDS in a HIV-1-infected female cohort in Thailand.

AIDS 2010 Jul;24(11):1625-31

National institute of Health, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand.

Objective: To investigate association of TIM1 sequence variations with HIV/AIDS progression.

Introduction: : HIV-1 infected individuals have wide variations in disease progression including AIDS. T cell immunoglobulin and mucin 1 (TIM1) is a cell surface protein involved in the regulation of Th1/Th2 immune response.

Materials And Methods: We sequenced the highly polymorphic exon 4 of TIM1 from 246 individuals of HIV-1 infected Thai female cohort to determine their TIM1 haplotypes. Associations of TIM1 haplotypes with baseline clinical data (sero-status, plasma viral load, CD4 cell count, and symptomatic AIDS) and survival status during 3 years of follow-up were evaluated.

Results: Seven TIM1 haplotypes, D3-A, D4, D3-C, D1, W-A, W-C, and D3-C*, were found in the cohort. Patients possessing the D3-A haplotype showed trends towards higher CD4 cell count (P = 0.06) and lower proportion of AIDS-related symptoms (P = 0.022) than the other patients at the baseline. Kaplan-Meier analysis demonstrated that patients carrying the D3-A haplotype had a better survival rates (P = 0.019) than the others. D3-A haplotypes was tightly linked to the lower expression levels of TIM1.

Conclusion: TIM1 D3-A haplotype is associated with the delay of disease progression to AIDS in the HIV-1 infected Thai females.
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http://dx.doi.org/10.1097/QAD.0b013e32833a8e6dDOI Listing
July 2010

Effects of CYP2B6 G516T polymorphisms on plasma efavirenz and nevirapine levels when co-administered with rifampicin in HIV/TB co-infected Thai adults.

AIDS Res Ther 2010 Mar 26;7. Epub 2010 Mar 26.

Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.

Background: Cytochrome P450 2B6 (CYP2B6) metabolizes efavirenz and nevirapine, the major core antiretroviral drugs for HIV in Thailand. Rifampicin, a critical component of tuberculosis (TB) therapy is a potent inducer of CYP enzyme activity. Polymorphisms of CYP2B6 and CYP3A4 are associated with altered activity of hepatic enzyme in the liver and pharmacokinetics resulting in treatment efficacy. This study aimed to investigate whether CYP2B6 or CYP3A4 polymorphisms had effects on plasma efavirenz and nevirapine concentrations when co-administered with rifampicin in HIV/TB co-infected Thai adults.

Results: We studied 124 rifampicin recipients with concurrent HIV-1/TB coinfection, receiving efavirenz (600 mg/day) (n = 65) or nevirapine (400 mg/day) (n = 59) based antiretroviral therapy (ART). The frequencies of GG, GT and TT genotypes of CYP2B6-G516T were 38.46%, 47.69% and 13.85% in efavirenz group and 44.07%, 52.54% and 3.39% in nevirapine group, respectively. The mean 12-hour post-dose plasma efavirenz concentration in patients with TT genotype at weeks 6 and 12 of ART and 1 month after rifampicin discontinuation (10.97 +/- 2.32, 13.62 +/- 4.21 and 8.48 +/- 1.30 mg/L, respectively) were significantly higher than those with GT (3.43 +/- 0.29, 3.35 +/- 0.27 and 3.21 +/- 0.22 mg/L, respectively) (p < 0.0001) or GG genotypes (2.88 +/- 0.33, 2.45 +/- 0.26 and 2.08 +/- 0.16 mg/L, respectively) (p < 0.0001). Likewise, the mean 12-hour post-dose plasma nevirapine concentration in patients carrying TT genotype at weeks 6 and 12 of ART and 1 month after rifampicin discontinuation (14.09 +/- 9.49, 7.94 +/- 2.76 and 9.44 +/- 0.17 mg/L, respectively) tended to be higher than those carrying GT (5.65 +/- 0.54, 5.58 +/- 0.48 and 7.03 +/- 0.64 mg/L, respectively) or GG genotypes (5.42 +/- 0.48, 5.34 +/- 0.50 and 6.43 +/- 0.64 mg/L, respectively) (p = 0.003, p = 0.409 and p = 0.448, respectively). Compared with the effects of CYP2B6-516TT genotype, we could observe only small effects of rifampicin on plasma efavirenz and nevirapine levels. After 12 weeks of both drug regimens, there was a trend towards higher percentage of patients with CYP2B6-TT genotype who achieved HIV-1 RNA levels <50 copies/mL compared to those with GT or GG genotypes. This is the first report to demonstrate the effects of CYP2B6 G516T polymorphisms on plasma efavirenz and nevirapine concentrations when co-administered with rifampicin in HIV/TB co-infected Thai adults.

Conclusions: CYP2B6-TT genotype had impact on plasma efavirenz and nevirapine concentrations, while rifampicin co-administration had only small effects.
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http://dx.doi.org/10.1186/1742-6405-7-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2859392PMC
March 2010

Phenotypic studies on recombinant human immunodeficiency virus type 1 (HIV-1) containing CRF01_AE env gene derived from HIV-1-infected patient, residing in central Thailand.

Microbes Infect 2009 Mar 27;11(3):334-43. Epub 2008 Dec 27.

Thailand-Japan Research Collaboration Center on Emerging and Re-emerging Infections (RCC-ERI), Nonthaburi 11000, Thailand.

Human immunodeficiency virus type 1 (HIV-1) env genes were cloned from blood samples of HIV-1-infected Thai patients, and 35 infectious CRF01_AE envelope glycoprotein (Env)-recombinant viruses were established. In this report, we examined the neutralization susceptibility of these viruses to human monoclonal antibodies, 2G12, IgG1 b12, 2F5 and 4E10, pooled patient plasma, coreceptor antagonists and fusion inhibitor, T-20. The neutralization susceptibility of CRF01_AE Env-recombinant viruses to 2F5, 4E10, patient plasma, coreceptor antagonists and T-20 varied, while most viruses showed low susceptibility to 2G12 and IgG1 b12. Several dual-tropic viruses showed lower susceptibility to 2F5 and 4E10 than CXCR4- or CCR5-tropic viruses. Neutralization susceptibility of the CRF01_AE Env-recombinant virus to pooled patient plasma was negatively correlated with the length of the V1/V2 region or the number of potential N-linked glycosylation sites in conserved regions of gp120. No correlation was found between the coreceptor usage and neutralization susceptibility of the virus to T-20, whereas several dual-tropic viruses showed higher susceptibility to coreceptor antagonists than CXCR4- or CCR5-tropic viruses. We propose that these CRF01_AE Env-recombinant viruses are useful to further study the molecular mechanism of the susceptibility of CRF01_AE Env to neutralizing antibodies and viral entry inhibitors.
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http://dx.doi.org/10.1016/j.micinf.2008.12.008DOI Listing
March 2009

Genotypic characterization of CRF01_AE env genes derived from human immunodeficiency virus type 1-infected patients residing in central Thailand.

AIDS Res Hum Retroviruses 2009 Feb;25(2):229-36

Thailand-Japan Research Collaboration Center on Emerging and Re-emerging Infections, Department of Medical Sciences, Ministry of Public Health, Tiwanon Road, Muang, Nonthaburi, Thailand.

CRF01_AE is a major subtype of human immunodeficiency virus type 1 (HIV-1) circulating in Southeast Asia, including Thailand. HIV-1 env genes were amplified by polymerase chain reaction from blood samples of HIV-1-infected patients residing in Thailand in 2006, and cloned into the pNL4-3-derived reporter viral construct. Generated envelope protein (Env)-recombinant virus was examined for its infectivity, and then 35 infectious CRF01_AE Env-recombinant viruses were selected. Sequencing analysis revealed that the interclone variation of the deduced amino acid sequences was higher in CRF01_AE env genes isolated in 2006 than in those isolated in the early 1990s, suggesting that env gene variation has been increasing gradually among CRF01_AE viruses prevalent in Thailand. We also examined the characteristics of the deduced amino acid sequences of 35 CRF01_AE env genes. Our results may provide useful information to help in better understanding the genotype of env genes of CRF01_AE viruses currently circulating in Thailand.
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http://dx.doi.org/10.1089/aid.2008.0232DOI Listing
February 2009