U1RNP Antibody-Positive Neonatal Lupus: A Report of two Cases with Immunogenetic Studies

Abstract

Background.— Neonatal lupus erythematosus (NLE) is a distinct subset of lupus characterized by cutaneous findings (50%), cardiac conduction defects (50%), and autoantibodies to Ro (SS-A) antigen. HLA typing studies of Ro (SS-A) antibody—positive mothers of infants with NLE have shown an association with the HLA-DR3 phenotype. We report the clinical and serologic features of two infant-mother pairs who are U1RNP antibody positive and Ro (SS-A) antibody negative. HLA typing is reported on these infants, their mothers, and two additional infant-mother pairs with U1RNP antibody—positive lupus whose clinical features have been reported previously. Observations.— Cutaneous findings included malar erythema, annular and polycyclic plaques, and scales that resolved with residual telangiectasia and hyperpigmentation 6 months after birth. Systemic abnormalities, including complete heart block, were absent. HLA typing revealed HLA-DR3 in two of four mothers, HLA-DR4 and HLA-DRw53 in two of four mothers, and either HLA-DQ1 or HLA-DQ3 in four of four mothers. No distinct HLA associations were seen in the three infants examined. Conclusions.— The spectrum of cutaneous disease in U1RNP antibody—positive infants is similar to Ro (SS-A) antibody—positive infants with NLE. Complete heart block was not a feature of U1RNP antibody—positive NLE. HLA typing studies show a more diverse immunogenetic pattern in U1RNP antibody—positive mothers of infants with NLE compared with Ro (SS-A) antibody—positive mothers. © 1992, American Medical Association. All rights reserved.