Data from this large series substantiate that autoantibody-associated CHB is not coincident with major structural abnormalities, is most often identified in the late second trimester, carries a substantial mortality in the neonatal period and frequently requires pacing. The recurrence rate of CHB is at least two- to three-fold higher than the rate for a mother with anti-SSA/Ro-SSB/La antibodies who never had an affected child, supporting close echocardiographic monitoring in all subsequent pregnancies, with heightened surveillance between 18 and 24 weeks of gestation.

Clinical, serologic, and genetic findings in Sjögren's syndrome patients were correlated with quantitative determinations for antibody against Ro (SS‐A), La (SS‐B), and nRNP (Sm) using newly developed, sensitive solid‐phase assays. In 86 Sjögren's syndrome patient sera, more than 96% had anti‐Ro (SS‐A), and 87% had anti‐La (SS‐B), spanning a 4.8 log10 range of autoantibody concentration, whereas only 95% of the patients had anti‐nRNP (Sm). Low levels of anti‐Ro (SS‐A) and anti‐La (SS‐B) were found in 10% and 12.5%, respectively, of the 40 normal control sera. In Sjögren's syndrome patients, the level of anti‐Ro (SS‐A) correlated strongly with that of anti‐La (SS‐B) (r = 0.80; P 0.0001) but not with the level of anti‐nRNP (Sm). We found much higher levels of anti‐Ro (SS‐A) and anti‐La (SS‐B) in patients with purpura, leukopenia, lymphopenia, and increased polyclonal gamma globulins than in those without these conditions (between 4.3‐fold and 17‐fold higher; P < 0.001 to P < 0.05). Anti‐Ro (SS‐A) and anti‐La (SS‐B) levels correlated with the rheumatoid factor titer and with the concentrations of total globulin, IgG, and IgA, but not with the IgM concentration. The association of rheumatoid factor titer with levels of anti‐Ro (SS‐A) and anti‐La (SS‐B) occurred only in patients with primary Sjögren's syndrome. Antinuclear antibody titers correlated with levels of anti‐Ro (SS‐A) and anti‐nRNP (Sm). HLA‐DR3‐positive patients had higher levels of anti‐Ro (SS‐A) and anti‐La (SS‐B).

Primary Sjögren's syndrome is an autoimmune disorder characterized by dryness of the mouth and eyes. The human leukocyte antigen (HLA) locus DQ is related to the primary Sjögren's syndrome autoantibodies that bind the RNA proteins Ro/SSA and La/SSB. Both DQ1 and DQ2 alleles are associated with high concentrations of these autoantibodies. An analysis of all possible combinations at DQ has shown that the entire effect was due to heterozygotes expressing the DQ1 and DQ2 alleles. These data suggest that gene interaction between DQ1 and DQ2 (or alleles at associated loci), possibly from gene complementation of trans-associated surface molecules, influences the autoimmune response in primary Sjögren's syndrome.

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