Together with the change in B1 element content in exDNA, we revealed that treatment with DNase I led to a decrease in the content of L1 elements in blood exDNA (statistically insignificant) and an essential decrease in Lx elements, concluding that Lx repeats could serve as markers of carcinogenesis, particularly for tumours of epithelial origin. The gene discussed is DNASE1; the disease is neoplasm.