Protein C Deficiency: An absence or deficiency in PROTEIN C which leads to impaired regulation of blood coagulation. It is associated with an increased risk of severe or premature thrombosis. (Stedman's Med. Dict., 26th ed.)Protein C: A vitamin-K dependent zymogen present in the blood, which, upon activation by thrombin and thrombomodulin exerts anticoagulant properties by inactivating factors Va and VIIIa at the rate-limiting steps of thrombin formation.Ascorbic Acid Deficiency: A condition due to a dietary deficiency of ascorbic acid (vitamin C), characterized by malaise, lethargy, and weakness. As the disease progresses, joints, muscles, and subcutaneous tissues may become the sites of hemorrhage. Ascorbic acid deficiency frequently develops into SCURVY in young children fed unsupplemented cow's milk exclusively during their first year. It develops also commonly in chronic alcoholism. (Cecil Textbook of Medicine, 19th ed, p1177)Factor V Deficiency: A deficiency of blood coagulation factor V (known as proaccelerin or accelerator globulin or labile factor) leading to a rare hemorrhagic tendency known as Owren's disease or parahemophilia. It varies greatly in severity. Factor V deficiency is an autosomal recessive trait. (Dorland, 27th ed)Scurvy: An acquired blood vessel disorder caused by severe deficiency of vitamin C (ASCORBIC ACID) in the diet leading to defective collagen formation in small blood vessels. Scurvy is characterized by bleeding in any tissue, weakness, ANEMIA, spongy gums, and a brawny induration of the muscles of the calves and legs.Blood Coagulation Disorders: Hemorrhagic and thrombotic disorders that occur as a consequence of abnormalities in blood coagulation due to a variety of factors such as COAGULATION PROTEIN DISORDERS; BLOOD PLATELET DISORDERS; BLOOD PROTEIN DISORDERS or nutritional conditions.Purpura Fulminans: A severe, rapidly fatal reaction occurring most commonly in children following an infectious illness. It is characterized by large, rapidly spreading skin hemorrhages, fever, or shock. Purpura fulminans often accompanies or is triggered by DISSEMINATED INTRAVASCULAR COAGULATION.Protein S: The vitamin K-dependent cofactor of activated PROTEIN C. Together with protein C, it inhibits the action of factors VIIIa and Va. A deficiency in protein S; (PROTEIN S DEFICIENCY); can lead to recurrent venous and arterial thrombosis.Thrombophlebitis: Inflammation of a vein associated with a blood clot (THROMBUS).Thrombophilia: A disorder of HEMOSTASIS in which there is a tendency for the occurrence of THROMBOSIS.Prothrombin: A plasma protein that is the inactive precursor of thrombin. It is converted to thrombin by a prothrombin activator complex consisting of factor Xa, factor V, phospholipid, and calcium ions. Deficiency of prothrombin leads to hypoprothrombinemia.Factor V: Heat- and storage-labile plasma glycoprotein which accelerates the conversion of prothrombin to thrombin in blood coagulation. Factor V accomplishes this by forming a complex with factor Xa, phospholipid, and calcium (prothrombinase complex). Deficiency of factor V leads to Owren's disease.Antithrombin III Deficiency: An absence or reduced level of Antithrombin III leading to an increased risk for thrombosis.VermontPedigree: The record of descent or ancestry, particularly of a particular condition or trait, indicating individual family members, their relationships, and their status with respect to the trait or condition.L-Gulonolactone Oxidase: An enzyme involved in the metabolism of ASCORBIC ACID and aldarate. It catalyzes the oxidation of L-gulono-1,4-lactone to L-xylo-hex-3-ulonolactone.Thrombosis: Formation and development of a thrombus or blood clot in the blood vessel.Protein S Deficiency: An autosomal dominant disorder showing decreased levels of plasma protein S antigen or activity, associated with venous thrombosis and pulmonary embolism. PROTEIN S is a vitamin K-dependent plasma protein that inhibits blood clotting by serving as a cofactor for activated PROTEIN C (also a vitamin K-dependent protein), and the clinical manifestations of its deficiency are virtually identical to those of protein C deficiency. Treatment with heparin for acute thrombotic processes is usually followed by maintenance administration of coumarin drugs for the prevention of recurrent thrombosis. (From Harrison's Principles of Internal Medicine, 12th ed, p1511; Wintrobe's Clinical Hematology, 9th ed, p1523)Protein C Inhibitor: A member of the serpin family of proteins that is found in plasma and urine. It is dependent on heparin and is able to inhibit activated PROTEIN C; THROMBIN; KALLIKREIN; and other SERINE ENDOPEPTIDASES.Ascorbic Acid: A six carbon compound related to glucose. It is found naturally in citrus fruits and many vegetables. Ascorbic acid is an essential nutrient in human diets, and necessary to maintain connective tissue and bone. Its biologically active form, vitamin C, functions as a reducing agent and coenzyme in several metabolic pathways. Vitamin C is considered an antioxidant.Thromboembolism: Obstruction of a blood vessel (embolism) by a blood clot (THROMBUS) in the blood stream.Venous Thrombosis: The formation or presence of a blood clot (THROMBUS) within a vein.Heterozygote: An individual having different alleles at one or more loci regarding a specific character.Anticoagulants: Agents that prevent clotting.Point Mutation: A mutation caused by the substitution of one nucleotide for another. This results in the DNA molecule having a change in a single base pair.Saposins: A group of four homologous sphingolipid activator proteins that are formed from proteolytic cleavage of a common protein precursor molecule referred to as prosaposin.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Activated Protein C Resistance: A hemostatic disorder characterized by a poor anticoagulant response to activated protein C (APC). The activated form of Factor V (Factor Va) is more slowly degraded by activated protein C. Factor V Leiden mutation (R506Q) is the most common cause of APC resistance.Cerebral Infarction: The formation of an area of NECROSIS in the CEREBRUM caused by an insufficiency of arterial or venous blood flow. Infarcts of the cerebrum are generally classified by hemisphere (i.e., left vs. right), lobe (e.g., frontal lobe infarction), arterial distribution (e.g., INFARCTION, ANTERIOR CEREBRAL ARTERY), and etiology (e.g., embolic infarction).