Anti-Ro/SSA-p200 antibodies in the prediction of congenital heart block. An Italian multicentre cross-sectional study on behalf of the 'Forum Interdisciplinare per la Ricerca nelle Malattie Autoimmuni (FIRMA) Group'.

OBJECTIVES: To verify the association between the presence of specific anti-52 Ro/SSA-p200 antibodies and congenital heart block (CHB). METHODS: 207 pregnant Italian women carrying anti-Ro/SSA Ab were retrospectively evaluated. Anti-p200 Ab were investigated in the mothers' sera by ELISA (Euro-Diagnostica,Wieslab SS-A p200). RESULTS: CHB occurred in 42 children (34 complete CHB), whereas 165 were not affected. All CHB cases were previously identified with an ELISA screening for anti-Ro/SSA 60 kD Ab. Anti-p200 Ab were more frequently positive (81.0% vs. 59.1%, p=0.013) and at a higher titer in CHB mothers (Absorbance ratio: 2.030 (0.208-4.052) vs. 0.925 (0.200-3.816); p=0.017). This association was maintained even when the 42 mothers of children with CHB were compared with a control group matched for age and diagnosis (80.9% vs. 50.0%; p=0.006). The presence of anti-p200 Ab provided an odds ratio (OR) for CHB of 2.98 (CI: 1.30-6.83), which was higher than that of other variables, such as maternal disease and other antibody specificities. CHB risk significantly decreased in the absence of this fine specificity (OR:0.34, CI: 0.15-0.77). However, while the negative predictive value related to anti-Ro/SSA 60 kD Ab ELISA was 100%, almost 20% of mothers negative for anti-p200 Ab delivered babies with CHB. CONCLUSIONS: Anti-p200 antibodies seem to be associated with CHB with a higher probability than anti-Ro/SSA Ab, and therefore may be an additional test to identify mothers at higher risk to deliver affected children. An ELISA screening for anti-Ro/SSA 60 kD Ab is nevertheless mandatory given the probability of developing CHB also in the absence of anti-p200 Ab.