vWF activity measured as ristocetin cofactor activity (Ricof) or collagen binding activity (CBA), which is measured in plasma and is not the same as RIPA (see below) which is ability of ristocetin to agglutinate platelet rich plasma.

The main subtypes of type 2 are 2A and 2M. In 2A there is a qualitative defect with absent HMW multimers and in 2M there is a qualitative defect but with HMW multimers present.

RIPA is ristocetin-induced platelet agglutination performed on a patient's platelet rich plasma. Only value of RIPA test is for detection of type 2B when RIPA is increased due to high affinity variant vWF which produces thrombocytopenia and reduced circulating level of VWF

Factor VIII is seldom low enough to cause the joint bleeds seen in haemophilia except in Type 3 which is a severe bleeding disorder.

Type 2N is rare autosomal recessive variant in which the VIII:C carrier function of vWF is reduced. May be misdiagnosed as haemophilia A but clue is that females are affected as well as males and autosomal recessive inheritance.

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