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Ascertaining a pathogenic alteration in the PROS1 gene of patient with congenital protein S deficiency
This test is not intended for prenatal diagnosis
This test detects pathogenic alterations in the PROS1 gene to delineate the underlying molecular defect in a patient with a laboratory diagnosis of thrombophilia due to protein S deficiency.
The gene target for this test is:
Gene name (transcript): PROS1 (GRCh37 [hg19] NM_000313)
Chromosomal location: 3q11.1
At Mayo Clinic, measurement of plasma free protein S antigen (PSTF / Protein S Antigen, Plasma) is performed as the initial testing for protein S deficiency. If the free protein S antigen is abnormal, then the total plasma protein S antigen will be performed to distinguish between types I and III protein S deficiency. For patients in whom hereditary protein S deficiency is strongly suspected and the free plasma protein S antigen level is normal, consideration should be given to testing of free protein S activity, S_FX / Protein S Activity, Plasma, for detecting type II protein S deficiency.
Genetic testing for protein S deficiency is indicated if:
- Free protein S antigen and/or activity is abnormally reduced
- Preanalytical variables and acquired causes of protein S deficiency have been excluded (eg, acute thrombosis, surgery, disseminated intravascular coagulation [DIC], liver disease, vitamin K deficiency, therapy with vitamin K antagonists such as warfarin, pregnancy, treatment with hormonal contraceptives, HIV infection, varicella, sickle cell disease, malignancy, nephrotic syndrome)
Custom Sequence Capture and Targeted Next-Generation Sequencing (NGS) Followed by Polymerase Chain Reaction (PCR) and Sanger Sequencing when appropriate.