Which disease is most commonly associated with a high titer of anti-Sm (anti-Smith) antibody?

Which disease is most commonly associated with a high titer of anti-Sm (anti-Smith) antibody?

• A. Mixed connective tissue disease (MCTD)
• B. Rheumatoid Arthritis (RA)
• C. Systemic Lupus Erythematosus (SLE)
• D. Scleroderma

Answer: (C)

The presence of a high titer of anti-Sm (anti-Smith) antibodies is most commonly associated with systemic lupus erythematosus (SLE). Anti-Sm antibodies are considered quite specific for SLE and are typically found in patients who have the disease. The presence of these antibodies can help in the diagnosis of SLE, particularly because they are linked to the disease's characteristic manifestations and can indicate an increased risk for renal involvement. While mixed connective tissue disease (MCTD) does involve anti-Sm antibodies, they are usually found alongside other antibodies, and the titers of anti-Sm in MCTD are generally not as high or as specific as they are in SLE. Similarly, rheumatoid arthritis and scleroderma are associated with different autoimmune markers and do not have a strong correlation with anti-Sm antibody presence. Thus, the specificity and prevalence of high anti-Sm titers in patients with SLE make this the correct choice.

The presence of a high titer of anti-Sm (anti-Smith) antibodies is most commonly associated with systemic lupus erythematosus (SLE). Anti-Sm antibodies are considered quite specific for SLE and are typically found in patients who have the disease. The presence of these antibodies can help in the diagnosis of SLE, particularly because they are linked to the disease's characteristic manifestations and can indicate an increased risk for renal involvement.

While mixed connective tissue disease (MCTD) does involve anti-Sm antibodies, they are usually found alongside other antibodies, and the titers of anti-Sm in MCTD are generally not as high or as specific as they are in SLE. Similarly, rheumatoid arthritis and scleroderma are associated with different autoimmune markers and do not have a strong correlation with anti-Sm antibody presence. Thus, the specificity and prevalence of high anti-Sm titers in patients with SLE make this the correct choice.