PURPOSE: Previous studies found a strong association between HLA-B*1502 and 
carbamazepine (CBZ)-induced Stevens-Johnson syndrome (SJS) in Han Chinese, but 
not in Caucasian populations. Even in Han Chinese, the HLA-B*1502 was not 
associated with CBZ-induced maculopapular eruptions (MPE). This study seeks to 
identify whether HLA-B*1502 is associated with CBZ- or phenytoin (PHT)-induced 
SJS or MPE in a Thai population.
METHODS: Eighty-one Thai epileptic patients between 1994 and 2007 from the 
Chulalongkorn Comprehensive Epilepsy Program were recruited. Thirty-one subjects 
had antiepileptic drug (AED)-induced SJS or MPE (6 CBZ-SJS, 4 PHT-SJS, 9 
CBZ-MPE, 12 PHT-MPE), and 50 were AED-tolerant controls.
RESULTS: For the first time, a strong association between HLA-B*1502 and 
PHT-induced SJS was found (p = 0.005). A strong association was also found 
between the HLA-B*1502 and CBZ-induced SJS (p = 0.0005), making Thai the first 
non-Chinese population demonstrating such an association. Some patients, who 
were HLA-B*1502 and suffered from CBZ-induced SJS, could be tolerant to PHT and 
vice versa. This suggests that HLA-B*1502 may be a common attribute required for 
a Thai patient to develop SJS from these two AEDs; other different elements, 
however, are also needed for each AED. In addition, no association between HLA-B 
alleles and CBZ- or PHT-induced MPE was found.
CONCLUSIONS: CBZ- and PHT-induced SJS, but not MPE, is associated with 
HLA-B*1502 allele in Thai population.