KNG1 mutations (c.618 T > G and c.1165C > T) cause disruption of the Cys206-Cys218 disulfide bond and truncation of the D5 domain leading to hereditary high molecular weight kininogen deficiency.

Background: High molecular weight kininogen (HMWK), encoded by the kininogen-1 (KNG1) gene, is a multifunctional glycoprotein closely associated with the initiation of blood coagulation, tumor growth, and other pathological processes.

Objective: We conducted a study on the clinical phenotype, genetic mutations, and molecular pathogenesis of a female patient with uterine leiomyosarcoma, who presented with HMWK deficiency and an isolated prolonged activated partial thromboplastin time (APTT).

Methods: Clinical phenotyping was conducted through APTT mixing studies, quantitative assessments of intrinsic coagulation factor activities, antigen levels of HMWK, and thromboelastography.