This abnormal bleeding tendency occurs in east Texas bleeding disorder, Amsterdam bleeding disorder, and a third and more extreme example described in 2021 by Karen L. Zimowski et al.Other mutations of factor V are associated with venous thrombosis. They are the most common hereditary causes for thrombophilia (a tendency to form blood clots). The most common one of these, factor V Leiden, is due to the replacement of an arginine residue with glutamine at amino acid position 506 (R506Q). All prothrombotic factor V mutations (factor V Leiden, factor V Cambridge, factor V Hong Kong) make it resistant to cleavage by activated protein C ("APC resistance"). It therefore remains active and increases the rate of thrombin generation. History
Until the discovery of factor V, coagulation was regarded as a product of four factors: calcium (IV) and thrombokinase (III) together acting on prothrombin (II) to produce fibrinogen (I); this model had been outlined by Paul Morawitz in 1905.The suggestion that an additional factor might exist was made by Paul Owren (1905–1990), a Norwegian physician, during his investigations into the bleeding tendency of a lady called Mary (1914–2002). She had suffered from nosebleeds and menorrhagia (excessive menstrual blood loss) for most her life, and was found to have a prolonged prothrombin time, suggesting either vitamin K deficiency or chronic liver disease leading to prothrombin deficiency. However, neither were the case, and Owren demonstrated this by correcting the abnormality with plasma from which prothrombin had been removed.
Benign lipoblastomatosis is a tumor consisting of fetal-embryonal adipocytes, frequently confused with a liposarcoma, affecting exclusively infants and young children, with approximately 90% of cases occurring before 3 years of age. : 626  The term lipoblastomatosis was first used by Vellios et al. in 1958, at which point the tumor became generally accepted as a distinctive entity. Today Diffuse lipoblastoma is the preferred term for Lipoblastomatosis. The tumor is rare, accounting for less than 1% of all childhood neoplasm, and it has been found to be more common in males than females. It often presents as an asymptomatic rapidly enlarging mass, occurring more often in the soft tissues of the extremities. See also
Myxoid lipoblastoma
List of cutaneous conditions

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