They also identified four associated haplotypes: HLA-DPA1*0202-DPB1*0501 and HLA-DPA1*0202-DPB1*0301 were associated with susceptibility to chronic hepatitis B and HLA-DPA1*0103-DPB1*0402 and HLA-DPA1*0103-DPB1*0401 showed a protective effect. The gene discussed is HLA-DPA1; the disease is chronic hepatitis B virus infection.