Pharmacogenetic Markers of Drug Hypersensitivity in a Thai Population.

Severe cutaneous adverse drug reactions (SCARs) including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reactions with eosinophilia and systemic symptoms (DRESS) are potentially life-threatening cutaneous reactions caused by several drugs. Recently, a number of genes encoding for human antigen presenting proteins, alleles, have been discovered as valid pharmacogenetic markers for prediction of these life-threatening reactions. This study was aimed to determine the distribution of alleles including the class I and class II genes in 183 unrelated individuals of a Thai population using high resolution genotyping in order to obtain 2-field data (4-digit resolution) and compare the frequencies of the alleles that have been proposed as markers of SCARs with other ethnics. Results revealed a high prevalence of pharmacogenetic markers of drug-induced SCARs e.g., for dapsone for carbamazepine and oxcarbazepine; and for allopurinol; and for co-trimoxazole. Whereas, low prevalence of pharmacogenetic markers of SCARs induced by abacavir, and phenytoin, were noticed. The allele frequencies of , and observed in a Thai population were significantly higher than those reported in Japanese and Caucasian populations. Similar to those observed in other Southeast Asian populations, low frequencies of and alleles were noted in the study population. Based on the frequencies of pharmacogenetic markers, Thai and other Southeast Asian populations may at higher risk of drug-induced SCARs compared with Caucasian population.