Genetic Association of Co‐Trimoxazole‐Induced Severe Cutaneous Adverse Reactions Is Phenotype‐Specific: HLA Class I Genotypes and Haplotypes

Co‐trimoxazole (CTX) causes various forms of severe cutaneous adverse reactions (SCARs). This case‐control study was conducted to investigate the involvement between genetic variants of human leukocyte antigen (HLA) and CYP2C9 in CTX‐induced SCARs, including Stevens‐Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) and drug reaction with eosinophilia and systemic symptoms (DRESS) in Thai patients. Thirty cases of CTX‐induced SCARs were enrolled and compared with 91 CTX‐tolerant controls and 150 people from the general Thai population. Cases comprised 18 SJS/TEN and 12 DRESS patients. This study demonstrated that genetic association of CTX‐induced SCARs was phenotype‐specific. HLA‐B*15:02 and HLA‐C*08:01 alleles were significantly associated with CTX‐induced SJS/TEN, whereas the HLA‐B*13:01 allele was significantly associated with CTX‐induced DRESS. In addition, a significant higher frequency of HLA‐A*11:01‐B*15:02 and HLA‐B*13:01‐C*03:04 haplotypes were detected in the group of CTX‐induced Stevens‐Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) and DRESS cases, respectively. Genetic association of CTX‐induced SCARs is phenotype‐specific. Interestingly, these association was observed only in HIV‐infected patients but not in non‐HIV‐infected patients

Pharmacogenomic study reveals new variants of drug metabolizing enzyme and transporter genes associated with steady-state plasma concentrations of risperidone and 9-hydroxyrisperidone in Thai autism spectrum disorder patients

The present study sought to investigate the genetic variants in drug metabolizing enzyme and transporter (DMET) genes associated with steady-state plasma concentrations of risperidone among Thai autism spectrum disorder (ASD) patients. ASD patients taking risperidone for at least one month were enrolled for this pharmacogenomic study. Genotyping profile was obtained using Affymetrix DMET Plus array interrogating 1931 variants in 231 genes. Steady-state plasma risperidone and 9-hydroxyrisperidone were measured using liquid chromatography/tandem mass spectrometry (LC-MS/MS) assay. The final analysis included 483 markers for 167 genes. Six variants, ABCB11 (c.3084A>G, c.*420A>G, c.*368G>A, and c.*236G>A) and ADH7 (c.690G>A and c.-5360G>A), were found to be associated with plasma concentrations of risperidone. 9-Hydroxyrisperidone and the total active-moiety levels were associated with six gene variants, SCLO1B1 (c.-11187G>A and c.521T>C), SLCO1B3 (c.334G>T, c.699A>G, and c.1557G>A), and SLC7A5 c.*438C>G. Polymorphisms in UGT2B4 c.*448A>G and CYP2D6 (c.1661G>C, c.4180G>C, and c.-2178G>A) showed considerable but not significant associations with metabolic ratio. This pharmacogenomic study identifies new genetic variants of DMET genes in monitoring risperidone therapy

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