Ro (SS‐A) antibody and antigen in a patient with congenital complete heart block

Congenital complete heart block is closely associated with the presence of anti‐Ro (SS‐A) autoantibodies. Quantitative solid‐phase assays for Ro (SS‐A) autoantigen and autoantibody have established the presence of Ro (SS‐A) in cardiac tissues and have been used to evaluate an informative pedigree. The propositus we describe here had complete congenital heart block and showed anti–Ro (SS‐A) binding of 13‐fold less than his normal HLA‐identical twin sister. Both had identical titers of antinuclear antibody. These data support the hypothesis that anti–Ro (SS‐A) may be directly involved in the pathogenesis of congenital complete heart block.