Gene expression can be identified by analyzing a DNA sequence. The DNA sequence can include a barcode sequence that corresponds to a particular gene. The barcode sequence can be produced during the expression of a gene by first adding a Homologous Directed Repair (HDR) template including the barcode sequence into the DNA sequence of the gene and then splicing the barcode sequence out of an RNA precursor during the expression of the gene. As the barcode sequence is made available from the RNA precursor, it can be added to the DNA strand using HDR. The resulting DNA strand can be sequenced and the sequence data can be analyzed to identify the barcode sequence within the DNA sequence, which provides an indicator of the expression of the gene in DNA rather than RNA.