HLA-B*5801
The HLA-B*5801 allele has been linked to side effects in certain Asian individuals upon taking drugs such as allopurinol.
Allopurinol[edit]
Han Chinese carriers of the HLA-B*5801 alleles were at much higher risk (odds ratio 580, CI: 34.4-9781, corrected p value = 4.7 x 10e-24) of severe cutaneous adverse reactions (SCAR), which include the drug hypersensitivity syndrome, Stevens-Johnson syndrome, and toxic epidermal necrolysis, upon taking allopurinol, a commonly prescribed medication for gout and hyperuricemia. All 51 (100%) participants who had allopurinol-SCAR were HLA-B*5801 positive, versus only 20 (15%) of 135 allopurinol-tolerant participants. [PMID 15743917
]
Pre-emptive HLA-B*5801 screening in Taiwan "significantly decreased the incidence of allopurinol-induced SCARs in Taiwanese medical centres". 2926 people of Han Chinese descent who were indicated to take allopurinol treatment (but had not done so previously) were genotyped; 571 people (19.6%) tested positive for HLA-B*5801 and were advised to avoid allopurinol. Amongst the 2173 participants who eventually took allopurinol and who were HLA-B*5801 negative, there were no incidents of SCARs versus an expected 7 incidents going from a historical background rate. [PMID 26399967]
The strong association between HLA-B*58:01 and allopurinol induced SCARs has been extended to ethnic groups other than the Han Chinese, including Thai, Japanese, Korean, and European groups; studies in Taiwan, Japan, Europe, and Israel have shown that allopurinol is now a major cause of such drug induced SCARs.[PMID 26399967]
Genotyping[edit]
Although there are some published methods involving imputation and multiple SNP testing, in general there does not currently appear to be a straightforward method to accurately define HLA-B*5801 status across all populations based solely on the unphased SNP data generated from any of the microarrays used commonly by the major DTC genomics companies.
Within populations, tag SNPs or haplotypes for the HLA-B*5801 allele have been reported as follows [PMID 16998491]; note that allele orientation should be as set here in SNPedia:
