Neonatal lupus.

Neonatal lupus, albeit rare, affords an excellent opportunity to examine a disease from bedside to bench. Over the past year there have been numerous publications covering clinical aspects and basic research. The timing of heart block is not random; bradycardia is most often identified between 16 and 24 weeks of gestation. Investigations have focused on this apparently vulnerable period and examined the expression of known (SSA/Ro-SSB/La), novel (p57, endogenous retrovirus-3), and cross-reactive (laminin) autoantigens in fetal hearts of varied ages and in adult hearts. Clinical studies are accumulating, but a unique maternal autoantibody profile is yet to be identified. Anti-52-kD responses, measured by enzyme-linked immunosorbent assay and immunoblot, continue to be a nearly universal finding in mothers whose children have neonatal lupus. The presence of anti-U1RNP in the absence of anti-SSA/Ro-SSB/La antibodies occurs only in cases of isolated cutaneous disease and not (to date) in mothers of infants with cardiac manifestations. Immunogenetically, mothers with affected children appear to be more closely related to Sjögren's syndrome than systemic lupus erythematosus. Asymptomatic mothers do not invariably become ill, and if an asymptomatic mother does develop lupus it is not likely to be life threatening. Heart block is associated with substantial morbidity and mortality. Although treatment of affected fetuses with dexamethasone has successfully diminished associated effusions, this therapy has not reversed established third-degree block. Treatment with sympathomimetics may be beneficial in fetuses with hydropic changes. Prophylactic therapies, other than serial echocardiographic evaluation, are not supported by any published data. To further efforts at both the bench and bedside, research registries were recently established in the United States and Canada.