In mice, the Serpina1 gene cluster is located on chromosome 12, spanning a 230 kb genomic region, and encompasses five liver-specific human SERPINA1 homologous genes, which are arranged in the following order: Serpina1b, Serpina1d, Serpina1a, Serpina1c, and Serpina1e. The B6-hSERPINA1 mouse is a humanized model constructed by replacing the mouse Serpina1 gene cluster (from ~10k upstream of mouse Serpina1e to ~5k downstream of mouse Serpina1b) with the human SERPINA1 gene (from ~30k upstream to ~5k downstream of human SERPINA1). Homozygous B6-hSERPINA1 mice are viable and fertile and can be used to study the pathogenic mechanisms of emphysema and chronic obstructive pulmonary disease (COPD), cirrhosis, and hepatocellular carcinoma, as well as to develop related therapeutic approaches.