HUMAN-COMPLEMENT FACTOR-H DEFICIENCY ASSOCIATED WITH HEMOLYTIC-UREMICSYNDROME

This study reports on six cases of deficiency in the human complement regulatory protein Factor H (FH) in the context of an acute renal dise ase. Five of the cases were observed in children presenting with idiop athic hemolytic uremic syndrome (HUS). Two of the children exhibited a homozygous deficiency characterized by the absence of the 150-kD form of Factor H and the presence, upon immunoblotting, of the 42-kD Facto r H-like protein 1 (FHL-1) and other FH-related protein (FHR) bands. S outhern blot and PCR analysis of DNA of one patient with homozygous de ficiency ruled out the presence of a large deletion of the FH gene as the underlying defect for the deficiency. The other four children pres ented with heterozygous deficiency and exhibited a normal immunoblotti ng pattern of proteins of the FH family. Factor H deficiency is the on ly complement deficiency associated with HUS. These observations sugge st a role for FH and/or FH receptors in the pathogenesis of idiopathic HUS.