PEDBASE.org - The Pediatric Database - Detailed information of FACTOR 12 DEFICIENCY

FACTOR XII DEFICIENCY

DEFINITION:

A coagulation disorder characterized by a deficiency in Factor XII but not resulting in a bleeding diathesis.

EPIDEMIOLOGY:

incidence: rare
age of onset:
- no clinical abnormalities
risk factors:
- familial - autosomal recessive
  - chrom.#: 5q33-qter
  - gene: coagulation factor XII

PATHOGENESIS:

1. Background

Factor XII is the first component of the Intrinsic Pathway which is activated by the conversion of proenzyme Factor XII to its activated enzyme (XIIa) when blood comes into contact with a non-endothelialized surface such as a damaged vessel wall
this disorder was first described in 1955 in a patient named Hageman

2. Genetic Defect

genetic defect -> deficiency of Factor XII

CLINICAL FEATURES:

1. Hematologic Manifestations

patients are asymptomatic and usually discovered on a screening test
some patients may have a thrombotic tendency

INVESTIGATIONS:

1. Serum

prolonged PTT
decreased Factor XII
- homozygotes - profound deficiency
- heterozygotes - 30-65% of normal
normal PT, bleeding time, thrombin time, platelet count

MANAGEMENT

no treatment as condition is asymptomatic

Pediatric Database - FACTOR 12 DEFICIENCY

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