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| {{CMG}}; {{AE}}{{RAK}}
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| ==Overview==
| | Cardiac surgery<ref name="pmid23447502">{{cite journal| author=Aya HD, Cecconi M, Hamilton M, Rhodes A| title=Goal-directed therapy in cardiac surgery: a systematic review and meta-analysis. | journal=Br J Anaesth | year= 2013 | volume= 110 | issue= 4 | pages= 510-7 | pmid=23447502 | doi=10.1093/bja/aet020 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23447502 }} </ref> |
| Protein S deficiency is an autosomal dominant thrombophilia, which leads to an increased risk of thromboembolic events. Protein S is a vitamin K-dependent glycoprotein and plays a role in anticoagulation. It is mainly a cofactor to the activated protein C (APC), which inactivates coagulation factors Va and VIIa and thereby controlling the coagulation cascade.
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| ==Historical Perspective==
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| Protein S was first discovered and purified in Seattle, Washington in 1979, and it was arbitrarily named protein S after the city it was discovered in. The function of this protein was still unknown; however, it was hypothesized that protein S plays a role in activating protein C. Protein S deficiency was first discovered in 1984 when two related individuals with recurrent thromboembolic events and normal coagulation tests were studied. At the time, protein C deficiency was usually associated with recurrent familial thrombosis. These individuals were found to have diminished anticoagulation activity with normal coagulation tests (including a normal protein C level), and when purified human protein S was added to their plasma, effective anticoagulation was restored. <ref name="pmid6239877">{{cite journal| author=Comp PC, Nixon RR, Cooper MR, Esmon CT| title=Familial protein S deficiency is associated with recurrent thrombosis. | journal=J Clin Invest | year= 1984 | volume= 74 | issue= 6 | pages= 2082-8 | pmid=6239877 | doi=10.1172/JCI111632 | pmc=425398 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=6239877 }} </ref>
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| ==Classification==
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| Protein S deficiency can be subdivided into three types depending on whether the abnormality affects total protein S level, free protein S level, and/or protein S function:
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| *'''Type I:''' Reduced total protein S, free protein S, and protein S function
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| It is the classic form of hereditary protein S deficiency. Total protein S levels drop to approximately 50% of normal values while free protein S levels collapse to almost 15% of the normal. On a genetic level, type I deficiency usually results from missense or nonsense mutations. On few occasions, microinsertions, microdeletions, and splice site mutations have occurred with this type.
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| *'''Type II:''' Normal total and free protein S, reduced protein S function
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| This form results from a qualitative defect and is very rare. The genetics behind this type isn't certain; however, some reports have linked it to missense mutations affecting the protein S's ability to bind to the activated protein C. <ref name="pmid8943854">{{cite journal| author=Simmonds RE, Ireland H, Kunz G, Lane DA| title=Identification of 19 protein S gene mutations in patients with phenotypic protein S deficiency and thrombosis. Protein S Study Group. | journal=Blood | year= 1996 | volume= 88 | issue= 11 | pages= 4195-204 | pmid=8943854 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8943854 }} </ref> <ref name="pmid7803790">{{cite journal| author=Gandrille S, Borgel D, Eschwege-Gufflet V, Aillaud M, Dreyfus M, Matheron C et al.| title=Identification of 15 different candidate causal point mutations and three polymorphisms in 19 patients with protein S deficiency using a scanning method for the analysis of the protein S active gene. | journal=Blood | year= 1995 | volume= 85 | issue= 1 | pages= 130-8 | pmid=7803790 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=7803790 }} </ref>
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| *'''Type III:''' Normal total protein S, reduced free protein S and protein S function
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| This is a quantitative defect.
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| {| class="wikitable sortable"
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| !Type
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| !Total Protein S
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| !Free Protein S
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| !Protein S Function
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| |-
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| |I
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| |↓
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| |↓
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| |↓
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| |-
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| |II
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| |↔
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| |↔
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| |↓
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| |-
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| |III
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| |↔
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| |↓
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| |↓
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| |}
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| ==Pathophysiology==
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| Protein S is produced by the hepatocytes, endothelial cells, and megakaryocytes. It has two methods of action in coagulation; however, it has to first get activated visa vitamin K-dependent gamma-carboxylation.
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| Protein S is a vitamin K-dependent glycoprotein, but it is not a zymogen of a serine protease enzyme. It serves as a cofactor for activated protein C, which inactivates procoagulant factors Va and VIIIa, reducing thrombin generation. Protein S also serves as a cofactor for activated protein C in enhancing fibrinolysis and can directly inhibit prothrombin activation via interactions with other coagulation factors
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| Mature gamma-carboxylated protein S circulates in two states: free, and bound to the complement component C4b-binding protein (C4b-BP). The free form comprises 30 to 40 percent of total protein S and is the only form of protein S that has cofactor activity for activated protein C
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| ==Clinical Features==
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| ==Differentiating [disease name] from other Diseases==
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| ==Epidemiology and Demographics==
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| ===Age===
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| ===Gender===
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| ===Race===
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| ==Risk Factors==
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| == Natural History, Complications and Prognosis==
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| == Diagnosis ==
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| ===Diagnostic Criteria===
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| === Symptoms ===
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| === Physical Examination ===
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| === Laboratory Findings ===
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| ===Imaging Findings===
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| === Other Diagnostic Studies ===
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| == Treatment ==
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| === Medical Therapy ===
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| === Surgery ===
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| === Prevention ===
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| ==References==
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| {{Reflist|2}}
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