5 WARNINGS AND PRECAUTIONS
The HLA-B*58:01 allele is a genetic marker for severe skin reactions indicative of hypersensitivity to allopurinol. Patients who carry the HLA-B*58:01 allele are at a higher risk of allopurinol hypersensitivity syndrome (AHS), but hypersensitivity reactions have been reported in patients who do not carry this allele. The frequency of this allele is higher in individuals of African, Asian (e.g., Han Chinese, Korean, Thai), and Native Hawaiian/Pacific Islander ancestry. Prior to starting ALOPRIM, consider testing for the HLA-B*58:01 allele in genetically at-risk populations. The use of ALOPRIM is not recommended in HLA-B*58:01 positive patients unless the benefits clearly outweigh the risks.
Prior to starting ALOPRIM, consider testing for the HLA-B*58:01 allele in genetically at-risk populations. Screening is generally not recommended in patients from populations in which the prevalence of HLA-B*58:01 is low, or in current allopurinol users, as the risk of SJS/TEN/DRESS is largely confined to the first few months of therapy, regardless of HLAB*58:01 status.
12.5 Pharmacogenomics
The HLA-B*58:01 allele is a genetic marker for severe skin reactions indicative of hypersensitivity to allopurinol [see Warnings and Precautions (5.1)]. The frequency of the HLAB*58:01 allele ranges from 8 to 10% in Han Chinese populations, about 8% in Thai populations, and about 6% in Korean populations based upon published literature and available databases. The frequency of the HLA-B*58:01 allele is about 4% in Blacks, about 1-2 % in indigenous peoples of the Americas and Hispanic populations, and <1% in people from European descent and Japanese.