Hmw/Lmw vWF multimers ratio (calculated by densitometric analysis as described in Materials and Methods) in recurrent HUS/TTP (top panel; controls, n = 13; acute, n = 6; remission, n = 9), in familial HUS/TTP (middle panel; healthy relatives, n = 53; acute, n = 3; remission, n = 13), and in sporadic HUS/TTP (lower panel; controls, n = 5; acute, n = 5; remission, n = 5). *P < .01 versus acute phase and controls; °P < .01, #P < .05 versus healthy relatives and controls; §P < .01 versus controls and versus remission.