External quality assessment for laboratory testing of HLA ‐B*15:02 allele in relation to carbamazepine therapy

Background Due to the significant risk of developing Stevens‐Johnson syndrome ( SJS ) and toxic epidermal necrolysis ( TEN ), the use of carbamazepine is not recommended in patients carrying the human leukocyte antigen B ( HLA ‐B ) *15:02 allele. In an effort to guarantee reliable community‐based HLA ‐B*15:02 testing throughout China, a HLA ‐B*15:02 genotyping external quality assessment ( EQA ) program was set up. Methods In 2016, 10 genomic DNA samples with known HLA ‐B*15:02 allele status were sent to 37 laboratories from 16 provinces with a request for routine HLA ‐B*15:02 screening. The samples were validated using Sanger sequencing by a reference laboratory. Both genotyping results and clinical written reports were evaluated. Results Thirty‐six of the participating laboratories correctly identified the HLA ‐B*15:02 allele status for all EQA samples. However, one lab failed to identify any positive challenges. The overall analytical sensitivity was 97.3% (180/185 challenges; 95% confidence interval: 93.8%‐99.1%) and the analytic specificity was 100% (185/185; 95% confidence interval: 98.0%‐100%). A review of the written reports showed that the clinical reporting for HLA ‐B*15:02 detection should be improved. Some essential information was missing, most notably laboratory information/contact, therapeutic recommendations, and methodology. Conclusion External quality assessment is valuable in assessing and improving the quality of laboratory testing of HLA ‐B*15:02 allele.