PREVALENCE OF MATERNAL Ro (SS-A) AND La (SS-B) AUTOANTIBODIES IN RELATION TO CONGENITAL HEART BLOCK

The prevalence of autoantibodies to ribonucleoprotein antigens in cases of congenital heart block was established using immunofluorescence, counterimmunoelectrophoresis, double immunodiffusion and Western blots. All of 35 mothers of babies with congenital heart block, none of five mothers of babies with other types of heart block, 10 of 29 women with connective tissue disease but no babies with heart block, four of 445 normal pregnant women and two of 109 healthy nonpregnant women had either Ro (SS-A) or La (SS-B) antibodies. Of 15 babies with congenital heart block, 10 of 10 who were less than 3 months old possessed antibody. Antibody titres in affected but not in normal infants were lower compared with their mothers' titres, suggesting deposition of antibodies in the baby's tissues. The findings indicate that placental transfer of anti-Ro (SS-A) or anti-La (SS-B) is essential for development of congenital complete heart block.