Ashkenazi Disorders: Mendelian

Factor XI Deficiency
(Plasma Thromboplastin Antecedent Deficiency,
PTA Deficiency, or Hemophilia C)

Factor XI binds to platelets to stop bleeding. Deficiency of Factor XI causes a (usually) mild bleeding disorder that can become more serious after surgery, tooth extraction, or injury. Individuals with this factor deficiency are prone to easy bruising, nosebleeds, or blood in their urine. Prolonged bleeding after childbirth can also occur. However, the severity of symptoms is highly variable, even between members of the same family. In addition, 20 – 50% of carriers (heterozygotes) also experience excessive bleeding.

Disease frequency:1 in 190 Ashkenazi Jews, 1 in 1,000,000 worldwide.
Carrier frequency:1 in 8 to 1 in 10 in Ashkenazi Jews.
Diagnosis:By a physician knowledgeable about the disorder, by measuring the Factor XI level in the blood, and by identifying a specific PTA gene mutation.
Inheritance:Autosomal recessive
Carrier testing:By measuring Factor XI level in blood or identifying a known mutation.
Prenatal diagnosis:Possible if a mutation has been identified in both carrier parents or an affected sibling.

Technical Information on Factor XI Deficiency

Additional Information:
National Hemophilia Foundation
116 West 32nd Street
11th Floor
New York, NY 10001
(212) 328-3700
fax: 212-328-3777
HANDI phone: (800) 42-HANDI
HANDI fax: (212) 328-3799

The Haemophilia Society
Chesterfield House
385 Euston Road
free phone helpline: 0800 018 6068
administration: + 44 20 7380 0600
fax: +44 20 7387 8220