Posted by Adam Awdish on
Human Total Factor XII ELISA Kit from Innovative Research was used in the following study:
Sheng-Chieh Chou, Ching-Yeh Lin, Hsuan-Yu Lin, Chen-Hsueh Pai, Cheng-Ye Yu, Su-Feng Kuo, Jen-Shiou Lin, Po-Te Lin, Mei-Hua Hung, Han-Ni Hsieh, Hsiang-Chun Liu & Ming-Ching Shen
International Journal of Hematology
June 8, 2022
Factor XII (FXII) deficiency is a condition that results in prolonged activation time of thromboplastin without being linked to excessive bleeding, and roughly 2% of otherwise healthy blood donors are reported to be deficient in FXII. Although FXII deficiency isn’t a cause of excessive bleeding, studies have linked it to recurrent abortions and concluded it is an essential contributor to thrombosis and inflammation.
The intrinsic coagulation pathway is activated by FXII via contact with negatively charged surfaces that induce changes in zymogen FXII. Following this, activated FXII (FXIIa) activates plasma prekallikrein into kallikrein, which then creates a cycle of more FXII activation. FXIIa also activates Factor XI, which then activates Factor IX before proceeding through the intrinsic coagulation pathway. Despite FIX activation occurring in hemostasis, this activation isn’t redundant, as FXIIa can also initiate the classic complement pathway simultaneously, thus promoting fibrinolysis.
The F12 gene has been linked to inherited severe FXII deficiency via either homozygous or compound heterozygous mutations of the gene. Further, a substitution of C to T at a non-coding area upstream of the F12 starting codon is well-known to cause a significant reduction in FXII protein translation, and this polymorphism is more common in Asian populations.
Although patients with FXII deficiency don’t need special management, they may still receive unnecessary plasma transfusions or delays in necessary procedures due to unaware physicians. Lack of awareness may also impact the likelihood of future studies on FXII deficiency, thus researchers in this study collected patients with severe congenital FXII deficiency and have been clinically testing and monitoring them since 1995.
Patients’ clinical, lab, and genetic test results were monitored alongside their cell expression of the F12 gene during the study. Blood samples were tested for FXII activity, antigen, and F12 gene cell expression; antigens were detected via ELISA and activity was measured by one stage clotting assay. Further in vitro observations revealed FXII mutations in some patients with severe FXII deficiencies, and one patient was discovered to have a previously unknown FXII mutation that results in a p.Gly542Ser substitution. Interestingly, the mutations observed in patients lead researchers to believe that these deficiencies may be genetically linked to Asian populations, specifically those of Taiwanese descent. The full-length FXII gene was then mapped and published.
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