Jean Amiral: Reagent-Dependent Factor X Activity in a Novel Calcium-Sensitive Variant
Jean Amiral, Founder of HYPHEN BioMed, Scientific Consultant at SH-Consulting, shared a post on LinkedIn:
“During ISTH in Paris, this July, we reported an interesting case of a new Calcium-dependent Factor X variant.
Patient’s plasma showed variable Prothrombin Time (PT) measurement and Factor X clotting activity depending on the PT reagent used.
Factor X chromogenic activity and Factor X antigen level were almost normal, although within the lower edge of normal range.
Clinical symptoms remained weak.
Complementary explorations revealed a new Factor X mutation, located at the Gamma-Carboxy-Glutamic domain, and a decreased binding to phospholipids in presence of calcium.
This effect was variable depending on the reagent used.
PT-Phen was the reagent revealing the highest decrease of Factor X coagulant activity (percentage) and low PT value (percentage).
Interestingly, when Calcium (CaCl2) concentration in the reagent was increased in percentage PT and Factor X coagulant activity progressively increased, until they reached a close value to the antigenic level.
This normalization was obtained with a 3-fold higher Calcium concentration than the one currently used.
Plasmas from Healthy population were not affected by the Calcium concentration increase when assayed with assays calibrated in the same working conditions.”
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