Control of gene expression is a general approach to treat diseases where there is too much or too little of a gene product. However, while there are many methods which are available to downregulate the expression of messenger RNA transcripts, very few strategies can upregulate the endogenous gene product. The vast majority of gene regulatory drugs which are commercially available or being developed are designed to knockdown gene expression (i.e. siRNAs, miRNAs, anti-sense, etc.). There exist some methods to enhance gene expression, such as the delivery of messenger RNAs; although, therapeutic delivery of such large and charged RNA molecules is technically challenging, inefficient, and may not be practical. There are also classical gene therapy approaches where a gene product is delivered as viral-encoded products (AAV or lentivirus-packaged). However, these methods suffer from not being able to accurately reproduce the correct alternatively spliced isoforms in the right ratios in cells.