High molecular weight kininogen (HMWK) deficiency is an autosomal recessive coagulation defect. It is known by a variety of names, including Fitzgerald trait, Flaujeac trait, and Williams trait. Patients with HWMK deficiency do not have a hemorrhagic tendency, but they exhibit abnormal surface-mediated activation of fibrinolysis. Fitzgerald trait represents a 'true' deficiency of HMWK, whereas Flaujeac and Williams traits represent total kininogen deficiency, in which both HMWK and low molecular weight kininogen (LMWK) are deficient. HMWK and LMWK are both encoded by the KNG1 gene (612358) (Bick, 2002; Takagaki et al., 1985). [from
OMIM]