Gene therapy encapsulates many forms of adding different nucleic acids to a cell. Gene augmentation adds a new protein coding gene to a cell. One form of gene augmentiation is gene replacement therapy, a treatment for monogenic recessive disorders where a single gene is not functional an additional functional gene is added. For diseases caused by multiple genes or a dominant gene, gene silencing or gene editing approaches are more appropriate but gene addition, a form of gene augmentation where new gene is added, may improve a cells function without modifying the genes that cause a disorder.