A newborn develops complete heart block requiring pacing. The mother has a history of arthralgia and photosensitive rash but no prior cardiac disease. Which maternal antibody is responsible for this complication?
- A Anti-Smith
- B Anti-Ro (SSA) ✓
- C Anti-dsDNA
- D Lupus anticoagulant
Correct answer: B. Anti-Ro (SSA)
Explanation
Neonatal lupus results from transplacental passage of maternal anti-Ro (SSA), often with anti-La (SSB), which bind fetal cardiac conduction tissue and cause scarring of the atrioventricular node, producing congenital complete heart block. Anti-Smith and anti-dsDNA do not cross to produce this phenotype, and they correlate with maternal disease activity rather than neonatal heart block. Lupus anticoagulant causes fetal loss through placental thrombosis, not conduction disease.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.