Severe systemic lupus erythematosus with nephritis in a boy with deficiency of the fourth component of complement.

A young boy with severe systemic lupus erythematosus was found to be totally deficient in the fourth component of complement. Family studies were consistent with an autosomal recessive mode of transmission and with linkage of the gene(s) determining C4 deficiency to the major histocompatibility complex; no disease states were associated with heterozygosity. This patient has had severe multisystem disease and immune complex glomerulonephritis presumably the alternative pathway of complement was utilized in the pathogenesis of his nephritis.