title: [Molecular biological analysis of hereditary thrombophilia--genetic characterization of protein S deficiency].
abstract: Protein S is a plasma glycoprotein, which functions as a cofactor for activated protein C in the protein C pathway and also directly inhibits factors Va and Xa, independently of protein C. In plasma, protein S circulates as a free molecule (40%) or in a complex with C4b-binding protein (60%). Only a free protein S acts as an anticoagulant and its activity is lost by binding to C4b-binding protein. The physiological importance of protein S has been established by observations in patients with hereditary protein S deficiency who have an increased risk of developing thrombosis. Several previous studies reported that hereditary protein S deficiency was as common as protein C deficiency and that approximately 5% of hereditary thrombophilia was caused by protein S deficiency. But molecular biological analysis of protein S deficiency is not as advanced as protein C deficiency because the genetic characterization of protein S deficiency is limited by the presence of the inactive pseudogene that is highly homologous to the active true gene. Only a few previous studies have examined the genetic features of hereditary protein S deficiency. Further investigation is needed to characterize the pathophysiology and molecular basis of hereditary protein S deficiency.
authors.affiliation: First Department of Internal Medicine, Nagoya University School of Medicine.
authors.forename: T
authors.initials: T
authors.lastname: Yamazaki
mesh_terms: D006801:Humans; D020151:Protein C Deficiency; D017293:Protein S / Q000502:physiology; D018455:Protein S Deficiency / Q000235:genetics*; D011544:Pseudogenes; D013927:Thrombosis / Q000235:genetics*
chemical_list: D017293:Protein S