PC Deficiency Testing: Thrombin-Thrombomodulin as PC Activator and Aptamer-Based Enzyme Capturing Increase Diagnostic...

Area of Science:

• Biochemistry
• Hematology
• Molecular Diagnostics

Background:

• Protein C (PC) activity assays are standard for detecting PC deficiency in thrombophilia workups.
• Current methods use Protac activation and chromogenic or clot-based detection, with variable diagnostic accuracy.
• Investigating alternative activation and detection methods is essential for improving diagnostic sensitivity.

Purpose of the Study:

• To evaluate the impact of different PC activation methods (Protac vs. thrombin-TM) and APC detection techniques on diagnostic accuracy.
• To compare chromogenic, clot-based, and aptamer-based assays for PC activity measurement.
• To identify optimal strategies for sensitive and accurate PC deficiency diagnosis.

Main Methods:

• Prospective cohort study of 31 patients with confirmed PC deficiency.
• Comparison of PC activation using Protac versus thrombin-thrombomodulin (TM) complex.
• Assessment of activated PC (APC) detection via chromogenic assay, clot-based assay, and an oligonucleotide-based aptamer assay.

Main Results:

• Chromogenic and clot-based assays identified 84% and 77% of PC deficient patients, respectively.
• The aptamer-based assay increased true-positive results to 87%.
• Replacing Protac with thrombin-TM for activation yielded true-positive results in all patients (100% sensitivity).

Conclusions:

• The method of PC activation critically influences the accuracy of PC activity testing.
• Thrombin-TM complex activation significantly improves diagnostic sensitivity compared to Protac.
• Aptamer-based APC detection offers high sensitivity, especially for mutations outside the active site, and is less prone to interference than clot-based assays.