In Von willebrand disease, there is –
Correct Answer: Defects in vWF
Description: Von willebrand disease is the most common hereditary coagulation disorder due to qualitative or quantitative defect in vWF. von Willebrand Disease von Willebrand disease is transmitted as an autosomal dominant disorder. It usually presents as spontaneous bleed- ing from mucous membranes, excessive bleeding from wounds, and menorrhagia. It is underrecognized, as the diagnosis requires sophisticated tests and the clinical manifestations often are quite mild. Actually, this disease is surprisingly prevalent, paicularly in persons of European descent. It is estimated that approximately 1% of people in the United States have von Willebrand disease, making it the most common inher- ited bleeding disorder. People with von Willebrand disease have compound defects in platelet function and coagulation, but in most cases only the platelet defect produces clinical findings. The exceptions are rare patients with homozygous von Willebrand disease, in whom there is a concomitant defi- ciency of factor VIII severe enough to produce features resembling those of hemophilia (described later on). The classic and most common variant of von Willebrand disease (type I) is an autosomal dominant disorder in which the quantity of circulating vWF is reduced. There is also a measur- able but clinically insignificant decrease in factor VIII levels. The other, less common varieties of von Willebrand disease are caused by mutations that produce both qualita- tive and quantitative defects in vWF. Type II is divided into several subtypes characterized by the selective loss of high- molecular-weight multimers of vWF. Because these large mul- timers are the most active form, there is a functional deficiency of vWF. In type IIA, the high-molecular-weight multimers are not synthesized, leading to a true deficiency. In type IIB, abnormal "hyperfunctional" high-molecular- weight multimers are synthesized that are rapidly removed from the circulation. These high-molecular-weight multiA mers cause spontaneous platelet aggregation (a situation reminiscent of the very-high-molecular-weight multimer aggregates seen in TTP); indeed, some people with type IIB von Willebrand disease have mild chronic thrombocytope- nia, presumably due to platelet consumption. Reference : Harsh Mohan textbook pathology, 7th edition.Pg no.314 Ref Robbins 9/e pg 455
Category:
Pathology
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