External Quality Assessment of Molecular Testing for HLA-B*58:01 Allele in Shanghai

Background/Objectives: Allopurinol, a first-line drug for gout and hyperuricemia, carries a risk of severe cutaneous adverse reactions (SCARs). Studies have established a strong association between HLA-B*58:01 and this adverse reaction. Although pre-treatment genotyping is recommended, the reliability of HLA-B*58:01 genetic testing varies across laboratories. This study aims to assess the performance of HLA-B*58:01 genetic testing of clinical laboratories in Shanghai through an External Quality Assessment (EQA) program, evaluating accuracy and standardization. Methods: The EQA program was carried out twice a year in 2023 and 2024. Each EQA sample panel consisted of five distinct samples, including HLA-B*58:01 allele-positive and -negative cell cultures. Sample panels were distributed to clinical laboratories through the cold chain system and results were analyzed and scored. Results: EQA samples used in this study were optimized for evaluating current HLA-B*58:01 genotyping assays, and the EQA samples were proved to be homogeneous and stable through each EQA period. In 2023, 17 and 16 clinical laboratories participated in the two EQA schemes; in 2024, 34 and 33 laboratories participated. A total of 14/17 (82.4%), 16/16 (100%), 33/34 (97.1%), and 33/33 (100%) laboratories achieved "optimal" scores. Conclusions: EQA results indicate that most of clinical laboratories in Shanghai exhibit constantly satisfactory performance for HLA-B*58:01 genotyping. However, a few laboratories still need further improvement. Additionally, EQA has demonstrated to be an important method for monitoring clinical laboratories' performance.