Evaluating the risk of dapsone hypersensitivity syndrome in Nepalese Leprosy Patients via HLA-B* 13:01 screening using real-time PCR and comparative meta-analysis of international data

Background: Dapsone Hypersensitivity Syndrome (DHS) is a serious debilitating condition which can develop after 2–8 weeks of dapsone treatment in varying proportions between genetically diverse populations. Approximately 10% of the affected individuals die, and DHS patients often spend weeks to months in the hospital, which impacts health and psychological morbidity and household financial burden. In recent years, a human leukocyte antigen, HLA-B*13:01, has been consistently associated with up to 85% of DHS cases across international population studies; however, the necessity of next generation sequencing (NGS) severely limits clinical applications in low resource contexts. Methodology/Principal Finding: To investigate HLA-B*13:01 associations with DHS among Nepalese leprosy cases, retrospective and active DHS cases and dapsone-tolerant controls treated at least for 3 months with multi-drug therapy (MDT) were sampled and screened by HLA-B*13:01 qPCR. In the present study we enrolled 34 DHS cases and 82 dapsone tolerant controls and found that the association is maintained in a multi-ethnic Nepali population with an Odds Ratio of 50.1 (95% CI: 15.0-166.6). A previously validated qPCR-based commercial kit was used in the study, and we revalidated the methodology (23 negative and 35 positives by commercial qPCR) using Next Generation sequencing (NGS) method and found a concordance rate of 98.3%. We meta-analyzed all eligible HLA-B*13:01 and DHS association studies and found a summary Odds Ratio of 61.86 (95% CI 32.60 - 117.4). As 23.5% of the DHS cases were HLA-B*13:01 negative in our study, further analyses of the HLA-B*13:01 positive and negative study participants revealed that HLA-B*13:01 positive DHS cases were significantly younger than HLA-B*13:01 negative DHS cases (35.5 years vs. 66 years, p = 0.0018). The positive predictive value of the HLA test in the Nepalese population was ~ 24. Conclusion: The study validates the association between HLA-B*13:01 and DHS in Nepalese leprosy population. Inclusion of a genetic screening test before starting MDT could potentially prevent significant proportion of DHS occurring in leprosy cases, especially in South Asian and Southeast countries. Author summary: Dapsone, primarily used to treat leprosy, can trigger dapsone hypersensitivity (DHS) which is a severe debilitating, drug allergy episode lasting weeks to months in people after taking daily dapsone for 2–8 weeks. DHS can result in severe morbidity requiring prolonged hospitalization with mortality occurring in roughly 10%. The genetic locus HLA-B*13:01 is a significant risk factor and has been reported in various populations to be present in 80–90% of DHS cases. Prevalence of HLA-B*13:01 may vary in different ethnic or regional populations, and thus a qPCR-based study with DNA sequence validation was performed to estimate the association between DHS and HLA-B*13:01 Nepalese leprosy cases. In our analysis, we found that DHS cases about 50 times more likely to be HLA-B*13:01 positive than controls. The association in our study was found to be within the range of meta-analysis association based on population studies in India, China, Taiwan, Indonesia, Thailand, and South Korea. These findings indicate the efficacy of HLA-B*13:01 qPCR pre-screening before initiation of dapsone treatment to prevent most DHS development, and thereby, reduce associated catastrophic health and economic impacts.