Methodology: Twenty - two cases of SCARs caused by allopurinol and confirmed by using established criteria, were recruited. Genomic DNA was extracted from whole peripheral blood with EDTA using Qiagen kits, as instructed by supplier. Polymerase chain reaction using sequence - specific primers was used to detect HLA-B*5801. Genotyping of the amplified products were determined using agarose gel electrophoresis. A random sample of positive samples was validated using direct DNA sequencing. After comparing results from both methodologies 100% agreement was found.
Results: A total of 22 patients comprised 13 SJS/TEN (59.1%), Overlap 1 (4.5%) and 8 HSS/DRESS (36.4%) were genotyped. Out of 22 individuals, 21 (95.9%) patients were positive for HLA-B*5801.
Conclusion: Our result suggests a strong association between HLA-B*5801 and allopurinol – induced SCARs in Vietnamese. These finding is the first to be described in the Vietnamese population. Considering that HLA-B*5801 is present in 6.5% of the general Vietnamese population, our study shows that there is a significant risk that someone carrying the HLA-B*5801 allele will suffer from a drug induced SCAR if treated with allopurinol. More individuals suffering from SCAR are also of a burden on the health system and thus needs to be addressed. Future studies will be performed on a larger sample of individuals followed by a case-control study.