Objective. To determine the frequency of systemic lupus erythematosus (SLE)—associated clinical manifestations, autoantibodies, and HLA class II alleles in a large cohort of patients with childhood-onset SLE.

Methods. Eighty children with SLE onset before age 18 (27 before age 11) were studied for the frequency of renal, neuropsychiatric, and hematologic complications as well as for anti—native DNA, Ro, La, Sm, and U1 RNP autoantibodies. HLA—DR, DQ, and DP alleles were determined by oligotyping. The results were compared with findings in 213 adults with SLE onset at or after age 18 years.

Results. Renal involvement was more frequent in those with childhood-onset SLE, especially those with onset before age 11 (82%, compared with 53% in adults). Anti—U1 RNP was more common in American blacks with SLE onset before age 18. HLA—DRB1*0301, DQA1*0501, DQB1*0201 was more common in Caucasians and DRB1*1503, DRB5*0101, DQA1*0102, DQB1*0602 in American blacks, regardless of age at SLE onset. Anti-Sm autoantibodies were most highly associated with HLA—DQA1*0102 and DQB1*0602.

Conclusion. While childhood-onset SLE shares many immunogenetic and serologic similarities to adultonset disease, important clinical differences nevertheless exist in children with this disease.