WBR0190
| Author | [[PageAuthor::Mahmoud Sakr M.D. (Reviewed by Yazan Daaboul, M.D.)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Immunology, MainCategory::Pathophysiology |
| Sub Category | SubCategory::Cardiology, SubCategory::Dermatology |
| Prompt | [[Prompt::A female neonate with severe bradycardia is rushed to the operating room for pacemaker placement. She is born to a 25-year-old African-American mother who has a medical history significant for an autoimmune disease with chronic joint pains, malar rash, and photosensitivity. The mother admits she has not received any prenatal care. Physical examination is remarkable for severe bradycardia and presence of erythematous annular lesions with central clearing and and raised red borders on the face and the scalp. An ECG prior to the procedure reveals a complete dissociation between the P waves and the QRS complexes. Screening for which auto-antibodies in the mother could have prevented this patient's condition?]] |
| Answer A | AnswerA::Anti-SSA/Ro and/or anti-SSB/La antibodies |
| Answer A Explanation | AnswerAExp::Neonatal lupus (NL) is presumed to result from transplacental passage of maternal anti-SSA/Ro and/or anti-SSB/La antibodies. |
| Answer B | AnswerB::Anti-RNP antibodies |
| Answer B Explanation | AnswerBExp::Anti-RNP antibodies are autoantibodies associated with mixed connective tissue disease and are also detected in nearly 40% of Lupus erythematosus patients. However, they're not the most common type of autoantibodies associated with NL |
| Answer C | AnswerC::Anti-double-stranded DNA (dsDNA) antibodies |
| Answer C Explanation | [[AnswerCExp::Anti-dsDNA antibodies are very specific for SLE, with studies quoting nearly 100%, and are therefore used in the diagnosis of SLE. Higher titres of anti-dsDNA antibodies are more suggestive of SLE and lower titres can be found in people without the disease. In contrast to the high specificity, estimates of 25-85% have been observed for the sensitivity of anti-dsDNA in SLE. However, they're not the most common type of autoantibodies associated with NL]] |
| Answer D | AnswerD::Anti-ribosomal P protein antibodies |
| Answer D Explanation | [[AnswerDExp::Anti-ribosomal P protein antibodies are autoantibodies directed against three phosphorylated protein (“P protein”) components of ribosomes are present in a minority of patients with systemic lupus erythematosus (SLE) and are highly specific for SLE, not NL]] |
| Answer E | AnswerE::Antiphospholipid antibodies |
| Answer E Explanation | [[AnswerEExp::Antiphospholipid syndrome is an autoimmune, hypercoagulable state caused by antiphospholipid antibodies. APS provokes blood clots (thrombosis) in both arteries and veins as well as pregnancy-related complications such as miscarriage, stillbirth, preterm delivery, or severe preeclampsia.]] |
| Right Answer | RightAnswer::A |
| Explanation | [[Explanation::Neonatal lupus is responsible for 80 to 95 percent of all cases of congenital complete heart block diagnosed in utero or in the neonatal period. The characteristic skin rash, and maternal history of SLE in addition to congenital heart block makes the diagnosis of neonatal lupus very likely. Neonatal lupus (NL) is presumed to result from transplacental passage of maternal anti-SSA/Ro and/or anti-SSB/La antibodies. Most infants with complete heart block have a mother with anti-SSA/Ro and anti-SSB/La antibodies. Screening for those antibodies would have been appropriate and may have lead initiation of in utero mineralcorticoids which has a potential usefulness in improving outcomes of neonates with NL. Educational Objective: Maternal antibodies against Ro and La are associated with complete congenital hear block in newborns. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Lupus, WBRKeyword::Neonatal lupus, WBRKeyword::Systemic lupus erythematosus, WBRKeyword::Autoimmune, WBRKeyword::Autoantibody, WBRKeyword::Rheumatology |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |