This strain is a humanized mouse model of the Xdh gene, generated by replacing the mouse Xdh gene with the complete human XDH gene sequence, including its untranslated regions (UTRs), exons, and introns. The B6-hXDH mice express the human XDH gene and xanthine oxidase protein in a pattern similar to the endogenous Xdh gene in mice, making their genetic, protein expression, and biochemical features highly comparable to humans. This strain serves as an ideal preclinical platform for studying the pathological mechanisms of hyperuricemia and gout and for developing novel xanthine oxidase inhibitors and nucleic acid therapies.