Congenital prekallikrein deficiency

Area of Science:

• Hematology
• Biochemistry

Background:

• Congenital prekallikrein (PK) deficiency is a rare inherited disorder characterized by a significant in vitro coagulation defect.
• Despite the severe laboratory findings, affected individuals typically exhibit minimal or no bleeding symptoms, a phenomenon not fully understood.
• The gene for PK is located on chromosome 4, and around 80 cases have been documented.

Purpose of the Study:

• To review the clinical and laboratory features of prekallikrein deficiency.
• To discuss diagnostic criteria and differentiate between true deficiency and abnormal PK forms.
• To explore the non-coagulative roles of PK and its relationship with kallikrein, bradykinin, and fibrinolysis.

Main Methods:

• Review of existing literature on prekallikrein deficiency.
• Analysis of diagnostic parameters including partial thromboplastin time (PTT), prothrombin time (PT), and thrombin time (TT).
• Discussion of immunological studies for PK classification and molecular biology findings.

Main Results:

• Diagnosis is confirmed by markedly prolonged PTT, normal PT and TT, with PTT correction upon plasma/serum addition and shortening with prolonged incubation.
• Immunological studies classify patients into true deficiency (approx. 70%) and abnormal PK forms.
• PK is a liver-synthesized glycoprotein, circulating partly complexed with high-molecular-weight kininogen, and cleaved by FXIIa.

Conclusions:

• Prekallikrein deficiency presents a paradox of severe in vitro coagulation abnormalities with a mild clinical bleeding phenotype.
• The condition does not confer protection against thrombosis, and associated risk factors can lead to bleeding or thrombotic events.
• Further molecular studies are needed to establish definitive genotype-phenotype correlations, and the non-coagulative functions of PK warrant additional investigation.