Neonatal lupus erythematosus

Neonatal lupus erythematosus is an autoimmune disease in an infant born to a mother with anti-Ro/SSA and with or without anti-La/SSB antibodies. The disease most commonly presents with a rash resembling subacute cutaneous lupus erythematosus and can have systemic abnormalities such as complete heart block or hepatosplenomegaly. Neonatal lupus is usually benign and self-limited. Many of the clinical manifestations are transient, but certain heart problems can be permanent. Diagnosis is based on maternal antibodies and clinical manifestations. Treatment and management is mainly supportive and focused on preventing complete heart block if possible. Ro/SSA and La/SSB are proteins found inside cells. Anti-Ro/SSA and anti-La/SSB are antibodies that form against these proteins. These antibodies can be seen in autoimmune diseases, the most common being Lupus and Sjögren's. Mothers can have these antibodies circulating in their blood without having any signs or symptoms of an autoimmune disease. Babies born to mothers with these antibodies have a chance of developing neonatal lupus erythematosus. This occurs when maternal anti-Ro/SSA and anti-La/SSB antibodies enter fetal circulation and affect neonatal organs by crossing the placenta using FcRn receptors. The mechanism in which the antibodies affect organs is not yet completely understood. For the heart, it is thought that these antibodies bind to cells in the heart that go through physiologic cell death during embryogenesis. This leads to heart cell injury which causes secondary fibrosis in the conduction system, ultimately causing heart block. These antibodies can also affect calcium channels which are needed to initiate action potentials. Disruption to action potential propagation can affect the AV and SA nodes which are part of the conduction system of the heart. Fetal susceptibility and environmental factors could also play a role in pathogenesis since not all infants develop congenital heart block even when exposed to antibodies. Neonatal lupus can present with several signs and symptoms.