Dried blood spot‐based host genome analysis technique targeting pathological associations with hepatitis B: Development and clinical application in the Cambodian population

Abstract Aim Reports of patients with hepatitis B have highlighted associations between polymorphisms in the human leukocyte antigen ( HLA ) ‐DPB1 , CXCL13 , and CXCR5 genes and disease pathology. Owing to its potential to contribute to the development of new diagnostic and therapeutic methods, we aimed to establish a reliable host genome analysis technique that can be used in countries with inadequate infrastructure. Method We compared multiple commercially available kits for dried blood spot (DBS)‐based sample collection to develop a basic DBS‐based host genome analysis technique. We then collected blood samples from Cambodian patients with hepatitis B and performed single‐nucleotide polymorphism genotyping and HLA allele typing by the DBS system. Result We were able to perform single‐nucleotide polymorphism genotyping and HLA allele typing with host DNA samples obtained using a combination of a HemaSpot™ filter paper‐based device and a SMITEST ® EX‐R&D DNA extraction kit. The accuracy of genotyping using samples obtained by this method was not inferior to one using samples obtained by venipuncture. In the Cambodian population, significant associations of HLA‐DPB1 *04:01 with protection against chronic hepatitis B virus (HBV) infection, and HLA‐DPB1 *05:01 and HLA‐DPB1 *13:01 with susceptibility to chronic HBV infection were identified. Conclusion Based on the DBS system, we clarified the associations of HLA‐DPB1 alleles with chronic HBV infection in the Cambodian population for the first time. Because the DBS is a low‐cost, durable, transportable, and easy‐to‐handle modality, genetic analysis based on the DBS system is a feasible strategy for obtaining a deeper understanding of HBV epidemiology, especially in middle‐ or low‐income countries.