Abstract: Objective To investigate the correlation between the decreased DNaseⅠ activity and the mutation of DNaseⅠgene in patients with systemic lupus erythematosus (SLE), through detecting an A→T mutation at the position 172 in the exonⅡof DNaseⅠgene. Methods The serum DNaseⅠactivities of 70 SLE patients were quantitatively measured by the DNA-methyl green substrate colorimetry. The DNaseⅠ gene in 100 SLE patients was analyzed by restriction fragment length polymorphism(RFLP) to detect the existence of A→T mutation at position 172 in the exon Ⅱof DNaseⅠgene. The mutation might lead to a NSPⅠendonuclease location which could be digested by NSPⅠ. Results The mutation wasn not found in SLE patients. Conclusion There is no A→T mutation at the position 172 in the exonⅡof DNaseⅠgene in our SLE patients, and the low DNaseⅠ activity in SLE patients may not be associated with such a change.

Key words: Lupus erythematosus, systemic, Deoxyribonuclease I, Mutation