Platelet aggregation occurs in congenital afibrinogenaemia despite the absence of fibrinogen or its fragments in plasma and platelets, as demonstrated by immunoenzymology - Soria, J; Soria, C; Borg, J Y; Mirshahi, M; Piguet, H; Tron, P; Fessard, C; Caen, J P (Br J Haematol, 1985)