Provided is a platform for expressing a protein of interest by artificially manipulating the liver, and more particularly, to a platform for alleviating or treating a genetic disorder or improving a body function by inducing expression by inserting a transgene (e.g., a therapeutic gene) which can function or be expressed normally, into a high-expression secretory gene, instead of a disease gene which functions or is expressed abnormally. The high-expression secretory gene includes the HP or APOC3 gene. The transgene includes one that is highly expressed using a promoter in a hepatocyte genome and is secretory out of the cell.