the present invention relates to a method for comparing and determining the gene expression level , which is very important in disease - related gene screening , early clinical diagnosis and medicine development . the present invention utilizes quantitative characteristics of bioluminescence analysis to compare gene expression levels of different individuals or samples in order to search for disease - related genes . the specific steps include : labeling the mrna of a given gene from different sources through a suitable method , and mixing the labeled fragments to obtain pcr templates ; performing a polymerase chain reaction using source - specific primers and a gene - specific primer ; and detecting the sequence of the amplified dna fragments by bioluminescence analysis , the base sequence in the sequencing profile representing the gene source , and the signal intensity of each base representing the gene expression level from the corresponding source .