Weakly positive anti-Scl-70 antibody indicates possible systemic sclerosis or other diseases such as mixed connective tissue disease. 1. Systemic sclerosis: anti-Scl-70 antibody is an anti-DNA topoisomerase I antibody. Weakly positive anti-Scl-70 antibody is commonly found in systemic sclerosis, and it is a specific antibody for this disease. Patients may have symptoms such as hard, swollen and tight skin, and it may damage other organs such as joints, lungs and heart. 2. Other diseases: Overlap syndrome or mixed connective tissue disease, mainly a combination of two or more diseases such as systemic sclerosis, systemic lupus erythematosus, dermatomyositis, rheumatoid arthritis, etc., will also show weakly positive anti-Scl-70 antibodies. Weakly positive anti-Scl-70 antibodies alone cannot confirm the diagnosis of the disease, and it is necessary to combine with other tests and the patient’s clinical symptoms and relevant medical history to make a comprehensive diagnosis. It is recommended that patients go to the hospital in time to identify the cause of the disease and actively standardize the treatment.