It has been verified through the analysis of the correlation between the expression level of the PRMT5 gene and cardiac troponin I (TnI) that the expression level of the PRMT5 gene is irrelevant to the level of cardiac troponin, but the level of cardiac troponin can reflect the scope of myocardial infarction; thus, the expression level of the PRMT5 gene may be irrelevant to the scope of myocardial infarction. The gene discussed is TNNI3; the disease is myocardial infarction.