Prekallikrein deficiency

Severe Prekallikrein Deficiency Associated with Low Level of Factor XII: A Case Report

Hereditary deficiency of plasma prekallikrein (PPK) is a rare autosomal recessive disease. The affected patients are often asymptomatic and diagnosed incidentally during preoperative investigations or during hospitalization by isolated prolongation of activated partial thromboplastin time (aPTT). In this article, we report, a 46-year-old woman who was candidate for two invasive procedures (thyroid FNA and hysterectomy) and underwent preoperative evaluation. Due to prolonged aPTT with normal PT she was referred to the IBTO reference coagulation laboratory for specific coagulation assays. Ultimately, the examinations revealed severe PPK deficiency (<1%) with partial deficiency of factor XII level (25%).

Severe plasma prekallikrein deficiency: Clinical characteristics, novel KLKB1 mutations, and estimated prevalence

BACKGROUND

Severe plasma prekallikrein (PK) deficiency is an autosomal-recessive defect characterized by isolated activated partial thromboplastin time prolongation. To date, no comprehensive methodologically firm analysis has investigated the diagnostic, clinical, and genetic characteristics of PK deficiency, and its prevalence remains unknown.

PATIENTS/METHODS

We described new families with PK deficiency, retrieved clinical and laboratory information of cases systematically searched in the (gray) literature, and collected blood of these cases for complementary analyses. The Genome Aggregation Database (gnomAD) and the population-based Gutenberg Health Study served to study the prevalence of mutations and relevant genetic variants.

RESULTS

We assembled a cohort of 111 cases from 89 families and performed new genetic analyses in eight families (three unpublished). We identified new KLKB1 mutations, excluded the pathogenicity of some of the previously described ones, and estimated a prevalence of severe PK deficiency of 1/155 668 overall and 1/4725 among Africans. One individual reported with PK deficiency had, in fact, congenital kininogen deficiency associated with decreased PK activity. One quarter of individuals had factor XII clotting activity below the reference range. Four major bleeding events were described in 96 individuals, of which 3 were provoked, for a prevalence of 4% and an annualized rate of 0.1%. The prevalence of cardiovascular events was 15% (6% <40 years; 21% 40-65 years; 33% >65 years) for an annualized rate of 0.4%.

CONCLUSIONS

We characterized the genetic background of severe PK deficiency, critically appraised mutations, and provided prevalence estimates. Our data on laboratory characteristics and clinical course of severe PK deficiency may have clinical implications.

Prolonged activated partial thromboplastin time due to plasma prekallikrein deficiency: a case study and literature review on its clinical significance

: Activated partial thromboplastin time is a test assessing the intrinsic and common pathways of the coagulation cascade. We presented an asymptomatic case with isolated activated partial thromboplastin time prolongation. After excluding coagulation factor deficiency and lupus anticoagulant, the patient was diagnosed with plasma prekallikrein (PPK) deficiency. We reviewed the literature regarding effects of PPK deficiency which could have both antithrombotic and prothrombotic effects. At the moment, research supports that PPK deficiency in healthy adults rarely causes bleeding as it is not a major contributor of hemastasis; whereas in adults with multiple comorbidities or with predominant systemic inflammation, effects of PPK deficiency remain debatable. Further research is needed to clarify impacts of PPK deficiency in clinical settings.