Seronegative antiphospholipid syndrome (APS) is characterized by thrombosis and pregnancy loss without detectable lupus anticoagulant, anticardiolipin, or anti-β2GPI antibodies. A newly described antigen in seronegative APS is:
- A Anti-phosphatidylserine-prothrombin (aPS/PT) complex antibodies ✓
- B Anti-dsDNA antibody complex
- C Anti-Sm antibody
- D Anti-histone antibody
Correct answer: A. Anti-phosphatidylserine-prothrombin (aPS/PT) complex antibodies
Explanation
In patients with clinical features of APS (recurrent thrombosis or pregnancy morbidity) who test negative for the three classic criteria (lupus anticoagulant, anti-cardiolipin IgG/IgM, anti-β2GPI IgG/IgM), testing for anti-phosphatidylserine/prothrombin (aPS/PT) antibodies reveals positivity in a significant subset, explaining the 'seronegative' clinical picture. aPS/PT antibodies are now included in laboratory evaluation for APS. Anti-Sm and anti-histone are SLE-associated; anti-dsDNA is not specific to APS.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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