PRB4 and overlapping connective tissue disease: Similarly, anti-Ku and anti-U1 small nuclear ribonucleoprotein (anti-U1snRNP) antibodies are associated with mixed connective tissue disease (MCTD) or overlap syndromes, which were not fully evaluated here [2]. Rare autoantibodies, such as anti-PO, anti-Ku, and anti-U1snRNP, should not be overinterpreted in the absence of supporting clinical criteria, as they may occasionally be detected in other autoimmune conditions, transient inflammatory states, or even in asymptomatic individuals, underscoring the importance of clinical context in interpretation [2].