C4A and systemic lupus erythematosus: This A30-B18-DR7-SS haplotype was shared with (a) her SLE sibling S3 who had CNS lupus and lupus nephritis and passed away of intracerebral hemorrhage, (b) another sibling S1 who had high titers of antinuclear autoantibodies (ANA, 1:640) and low level of serum C4 (12 mg/dL), and (c) niece N3 who had low level of serum C4 (14 mg/dL) and exhibited positivity of antinuclear antibodies.