biostudies-literatureUnknown26Seidel HProtein C (PC) deficiency is associated with an increased risk for venous thromboembolism (VTE). In daily practice, exclusion of a hereditary PC deficiency is often based on a single determination of PC activity, by either clotting time-based or mostly chromogenic assay. However, diagnosis of hereditary PC deficiency is challenging due to several laboratory and clinical limitations. We compared the potential of PC activity values measured by either chromogenic or clotting time-based assay to predict a variation in the <i>PROC</i> gene. One hundred one (35%) of 287 patients carried variations within the <i>PROC</i> gene, including 2 previously not published variations. In 20 (20%) patients with identified variation, PC activity, determined by chromogenic assay, was within the reference rangClinical and applied thrombosis/hemostasis : official journal of the International Academy of Clinical and Applied Thrombosis/Hemostasis1076029620912028https://www.ebi.ac.uk/biostudies/studies/S-EPMC7288809biostudies-literatureLaboratory Limitations of Excluding Hereditary Protein C Deficiency by Chromogenic Assay: Discrepancies of Phenotype and Genotype.PMC7288809Kruppenbacher JPSeidel HHass MSHaracska BWesthofen PNaumann JfalseLaboratory Limitations of Excluding Hereditary Protein C Deficiency by Chromogenic Assay: Discrepancies of Phenotype and Genotype.Protein C (PC) deficiency is associated with an increased risk for venous thromboembolism (VTE). In daily practice, exclusion of a hereditary PC deficiency is often based on a single determination of PC activity, by either clotting time-based or mostly chromogenic assay. However, diagnosis of hereditary PC deficiency is challenging due to several laboratory and clinical limitations. We compared the potential of PC activity values measured by either chromogenic or clotting time-based assay to predict a variation in the <i>PROC</i> gene. One hundred one (35%) of 287 patients carried variations within the <i>PROC</i> gene, including 2 previously not published variations. In 20 (20%) patients with identified variation, PC activity, determined by chromogenic assay, was within the reference rang2020-01-01T00:00:00Z2020 Jan-Dec2025-04-04T08:39:35.542Z2025-04-04T08:39:35.542ZS-EPMC72888093230999410.1177/1076029620912028