Table 1.

Percentage of patients with decreased C3 plasma concentration in the various subgroups of atypical hemolytic uremic syndrome

	CFH mutation	CFI mutation	MCP mutation	C3 mutation	CFB mutation	THBD mutation	Anti -CFH Ab	None
Decreased C3 concentration (< 2SD) (% patients)	30-50%	20-30%	0-27%	70-80%	100%	50%	40-60%	up to 20%

Normal C3 plasma concentration does not eliminate the presence of a mutation in the complement system or of anti- CFH antibodies. Conversely, decreased C3 level signs the presence of a complement abnormality.

CFH: factor H; CFI: factor I; MCP: membrane cofactor protein; CFB: factor B; THBD: thrombomodulin; Ab, antibodies.