A pregnant woman with SLE delivers a neonate who is found to have a heart rate of 45 beats per minute. ECG confirms complete heart block. Which maternal antibody is most likely responsible?

1. A

   A. Anti-Ro antibody

2. B

   B. Anti-dsDNA antibody

3. C

   C. Anti-histone antibody

4. D

   D. Anti-Smith antibody

Appeared in: INI-CET EXAM -2026

Explanation

• Neonatal Lupus Erythematosus (NLE) is a passively acquired autoimmune condition where maternal IgG antibodies cross the placenta.
• The vast majority of NLE cases, particularly those involving cardiac issues, are associated with maternal Anti-Ro (SSA) antibodies.
• These antibodies target and damage the fetal cardiac conduction system, leading to inflammation, fibrosis, and irreversible conditions like complete heart block.
• The neonate's presentation of severe bradycardia (45 bpm) and ECG-confirmed complete heart block is a classic manifestation of cardiac NLE caused by Anti-Ro antibodies.

Why Other Options Were Wrong

• Option B: Anti-dsDNA antibodies are markers for SLE disease activity, especially lupus nephritis.
• Option C: Anti-histone antibodies are the hallmark of drug-induced lupus, not congenital heart block in neonatal lupus.
• Option D: Anti-Smith (Anti-Sm) antibodies are highly specific for diagnosing SLE but are not implicated in causing neonatal lupus or congenital heart block.

Related Visual

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pathophysiology of neonatal lupus and autoimmune-mediated congenital heart block as background academic context rather than a clinical decision trigger.
• Nurses should be aware that pregnant women with SLE or other autoimmune diseases (like Sjögren's syndrome) who are positive for Anti-Ro antibodies are at high risk for having a child with congenital heart block.
• Early identification is key. Fetal surveillance with serial echocardiograms is often recommended for at-risk pregnancies, typically starting between 16-18 weeks of gestation, to monitor for conduction abnormalities.
• A neonate born with complete heart block requires immediate pediatric cardiology consultation and may need a permanent pacemaker to ensure adequate cardiac output and prevent complications like heart failure.

How to Approach the Question

• First, analyze the clinical scenario: a mother with a known autoimmune disease (SLE) and a neonate with a specific, severe complication (complete heart block).
• Recognize that the question asks for the immunological link—the specific maternal antibody responsible for the neonatal condition.
• Recall the different types of autoantibodies associated with SLE and their primary clinical significance.
• Differentiate between antibodies that are diagnostic for SLE in the mother (Anti-dsDNA, Anti-Smith) and the specific antibody known to cross the placenta and cause neonatal complications.
• Identify Anti-Ro (SSA) as the key antibody responsible for neonatal lupus manifestations, especially congenital heart block.
• Eliminate the other options based on their known associations (lupus nephritis, drug-induced lupus, SLE diagnosis) which do not fit the neonate's presentation.

Concept Tested & Keywords

• Concept Tested: Pathophysiology of neonatal lupus and autoimmune-mediated congenital heart block.
• Stem keywords: pregnant woman, SLE, neonate, complete heart block, maternal antibody
• Lead-in keywords: most likely responsible
• Clinical cues: Maternal history of SLE combined with neonatal complete heart block strongly points to a specific transplacental antibody.

Question ID

QtqYSwbvs29rIHezpssStF

Copy ID

Reference Book

E6 Nelson Textbook of Pediatrics(2024) — Volume 1 pp. 1512-1514, 1511-1513

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 647-649