Which symptom is most commonly associated with neonatal lupus syndrome?

Neonatal lupus syndrome is primarily associated with a photosensitive rash, which is typically characterized by erythematous patches on sun-exposed areas of the skin. This rash arises due to the passage of maternal autoantibodies, mainly anti-Ro/SSA and anti-La/SSB antibodies, across the placenta to the fetus. The exposure to sunlight can exacerbate the skin manifestations, which is why the rash is photosensitive.

Infants with neonatal lupus may also present with other associated signs such as congenital heart block and hematological abnormalities, but the hallmark of the syndrome is indeed the rash. This understanding underscores the importance of recognizing skin manifestations in neonates as a crucial indicator of potential underlying autoimmune conditions, especially in mothers with autoimmune diseases like systemic lupus erythematosus.

In contrast, while neurological impairment, respiratory distress, and hypoglycemia can be serious conditions, they are not the primary or most characteristic symptoms associated with neonatal lupus syndrome, making the photosensitive rash the most relevant feature in this context.