The allele frequencies across Thailand five regions of HLA-B*15:02 (IMGT/HLA ID: HLA00165) which induces the risk of having SJS/TEN upon taking aromatic antiepileptic drug [CBZ, oxcarbazepine (OXC), phenytoin (PHT), and lamotrigine (LTG)], had no significant differences (p-value > 0.05) (Table 7). This evidence concerns the gene HLA-B and toxic epidermal necrolysis.