Sorted By Test Name - Mayo Medical Laboratories

F5DNA
81419
Adults: 65-140%
Normal, full-term newborn infants or healthy premature infants may have decreased levels (> or
=20%), which may not reach adult levels for > or =180 days postnatal.*
*See Pediatric Hemostasis References in Coagulation Studies in Special Instructions.
FACTOR IX INHIBITOR SCREEN
Negative
BETHESDA TITER
0 Units
Clinical References: 1. Feinstein DI, Rapaport, SI: Acquired inhibitors of blood coagulation. In
Hematology: Basic Principles and Practice. Edited by R Hoffman, EJ Benz Jr, SJ Shattil, et al. New York,
Livingstone Press, 1991, pp 1380-1394 2. Chitlur M, Warrier I, Rajpurkar M, et al: Inhibitors in factor IX
deficiency a report of the ISTH-SSC international FIX inhibitor registry (1997-2006). Haemophilia
2009;15(5):1027-1031
Factor V Leiden (R506Q) Mutation, Blood
Clinical Information: Venous thromboembolism (VTE) is a syndrome of deep vein thrombosis and
its complication, pulmonary embolism. Recent work highlights the role of both genetic heterogeneity and
genetic:environmental interaction in the etiology of VTE.(1) Plasma from 12% to 52% of VTE patients is
resistant to the anticoagulant effect of activated protein C (APC-resistance).(2) Approximately 90% of
patients with hereditary APC-resistance have a single nucleotide mutation of the coagulation factor V
gene that encodes for an arginine (R) to glutamine (Q) substitution at position 506 of the factor V protein
(FV Leiden).(3,5) In general, the FV Leiden allele population carrier frequency parallels the incidence of
VTE in that population. For example, the FV Leiden allele is common among populations of
Scandinavian and European ancestry (3%-7%), where the annual VTE incidence approaches 120 per
100,000. In contrast, the FV Leiden allele has yet to be detected in Asian or Japanese populations, where
VTE incidence is extremely low. Heterozygous FV Leiden carriers have an 8-fold risk increased for VTE,
while homozygous carriers have an 80- to 100-fold increased risk. Other genetic disorders causing
deficiency of antithrombin, protein C, protein S, or hyperhomocysteinemia are independently associated
with VTE. However, interaction of these genetic disorders with the FV Leiden allele markedly
compounds the risk for VTE. Genetic and environmental (clinical) risk factors also interact to compound
the risk for VTE. The VTE risk is increased 30-fold among women who are heterozygous FV Leiden
carriers and are receiving oral contraceptives. The VTE risk during pregnancy or the postpartum period
also is increased. Homozygous FV Leiden carriers have an increased risk for recurrent VTE, while the
risk for heterozygous carriers appears to be no different than the risk for noncarriers with VTE.
Controversy exists regarding the association between the FV R506Q allele and arterial occlusive disease
(eg, coronary artery disease, myocardial infarction, stroke); more studies are needed in order to answer
this question. Direct detection of the FV Leiden gene mutation can be performed on patient blood
leukocyte genomic DNA. See The Diagnosis and Treatment of Hypercoagulability States, Mayo Medical
Laboratories Communique 2001 Nov;26(11) for more information regarding diagnostic strategy.
Useful For: Direct mutation analysis should be reserved for patients with clinically suspected
thrombophilia and: -Activated protein C (APC)-resistance proven or suspected by a low APC-resistance
ratio -Family history of the factor V (FV Leiden) mutation It may be appropriate to screen those women
contemplating oral contraceptive use or pregnancy, with consideration of an alternative form of
contraceptive therapy or venous thromboembolism (VTE) prophylaxis during pregnancy or the
postpartum state for women with FV Leiden allele Knowledge of the FV Leiden allele status may alter
anticoagulation management of VTE patients.
Interpretation: The interpretive report will include specimen information, assay information,
background information, and conclusions based on the test results (normal, heterozygous factor V [FV
Leiden], homozygous FV Leiden).
Reference Values:
Negative
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