Factor XII (Hageman Factor) Deficiency: a rare harbinger of life threatening complications

Abstract

Hageman factor (factor XII) has a key role in activation of intrinsic coagulation system gauged by activated partial thromboplastin time (aPPT).
Hageman factor deficiency is more often an autosomal recessive condition, but an autosomal dominant inheritance is also reported. This condition
in its own is not known to cause bleeding complications rather is associated with paradoxical fatal thromboembolic complications. Exact prevalence
of this condition is not known, as under normal conditions they are asymptomatic. In literature, a prevalence of 2.3% has been reported in one study
on 300 patients presenting with complications. Homozygous patients has non-detectable levels of factor XII, while heterozygous individuals has
variable levels ranging from 20-60%. Hageman factor is a pro-coagulation protein initiating intrinsic pathway. Intrinsic pathway is activated either
by direct contact with a negative charged surface or by proteolytic activation on the endothelial cells via prekallikerin/kallikerin system. Factor XII as
an integral part of this system leads to factor XI activation resulting in production of thrombin orchestrated by intrinsic system. In addition, there is
concomitant activation of complement components C3 and C5 via C1-estrase activation. Patients with this condition are known to have spontaneous
thromboembolic complications although less common but are prone to life threatening complications under provocating circumstances. The aim of
this case report is to study the relation of factor XII deficiency and isolated raised activated partial thromboplastin time (aPPT) and how it can be
prevented. We are presenting a Saudi female patient, 29 years of age who presented to accident and emergency room (A&E room) of our hospital
with sudden severe breathlessness and chest pain