ARUP's Laboratory Test Directory

Hemophilia A (F8) 2 Inversions with Reflex to Sequencing and Reflex to Deletion/Duplication : 2001614
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Patient History for Hemophilia A or B Gene Testing
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Additional Technical Information


Mnemonic: F8 COMP

Ordering Recommendation: Recommended reflex test to detect the causal F8 mutation in established severe hemophilia A. For mild to moderate hemophilia A, Hemophilia A (F8) Sequencing (2001747) is preferred.
Methodology: Inverse Polymerase Chain Reaction/Sequencing/Multiplex Ligation-dependent Probe Amplification
Performed: Varies
Reported: Within 35 days
Specimen Required: Collect: Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).

Specimen Preparation: Transport 3 mL whole blood. (Min: 2 mL)

Storage/Transport Temperature: Refrigerated.

Stability (collection to initiation of testing): Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Interpretive Data: Background Information for Hemophilia A (F8) 2 Inversions with Reflex to Sequencing and Reflex to Deletion/Duplication:
Characteristics: Severe deficiency of factor VIII clotting activity is associated with spontaneous joint or deep tissue bleeding. Moderate or mild deficiency is associated with prolonged bleeding after tooth extractions, surgery, or injuries and recurrent or delayed wound healing.
Incidence: 1 in 4,000-5,000 live male births worldwide; rare in females.
Inheritance: X-linked recessive. Of simplex cases, 85 percent of mothers are carriers and 10-15 percent of boys have a de novo mutation.
Penetrance: 100 percent in males and 10 percent in females.
Cause: Deleterious F8 gene mutations.
Clinical Sensitivity: 98 percent.
Methodology for Inversions: F8 intron 22-A and intron 1 inversions detected by inverse PCR and electrophoresis.
Methodology for Sequencing: Bidirectional sequencing of the F8 coding region and intron-exon boundaries.
Methodology for Deletion/Duplication: Multiplex ligation-dependent probe amplification (MLPA) to detect large deletions/duplications in the F8 coding region.
Analytical Sensitivity & Specificity: 99 percent.
Limitations: Rare diagnostic errors can occur due to primer or probe site mutations. Regulatory region and deep intronic mutations, other than the F8 intron 22-A and intron 1 inversions, will not be detected.



Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.

See Compliance Statement C: www.aruplab.com/CS
Note: F8 inversion testing is performed on all specimens. If inversion testing does not explain the clinical scenario, then F8 gene sequencing will be added. If inversion testing and sequencing does not explain the clinical scenario, then deletion/duplication testing will be added. Additional charges apply.
CPT Code(s): 81403; if reflexed to Seq, add 81407; if reflexed to Del/Dup, add 81406
Cross References: F8 (Hemophilia A (F8) 2 Inversions with Reflex to Sequencing and Reflex to Deletion/Duplication) , Factor VIII (Hemophilia A (F8) 2 Inversions with Reflex to Sequencing and Reflex to Deletion/Duplication)