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Test Code GNHMA Hemophilia A, F8 Gene, Next-Generation Sequencing, Varies


Ordering Guidance


For male patients, this test should only be considered if clinical and family history, initial coagulation screens, and/or initial activity tests indicate a diagnosis of hemophilia A. For female patients, this test should only be considered if there is a confirmed diagnosis of hemophilia A in a family member or the patient has abnormally low factor VIII (FVIII) activity.

 

This test does not measure FVIII activity levels. For assessment of FVIII activity, order F8A / Coagulation Factor VIII Activity Assay, Plasma.

 

For individuals with bleeding symptoms and no known personal or family history of hemophilia A, consider ALBLD / Bleeding Diathesis Profile, Limited, Plasma or the specific factor assays.

 

This test does not evaluate for the presence of inversions in the F8 gene that can cause hemophilia A. If testing for possible inversions in the F8 gene is desired, order F8INV / Hemophilia A F8 Gene, Intron 1 and 22 Inversion Mutation Analysis, Whole Blood.

 

If genetic testing for hereditary bleeding disorders using a larger panel is desired, both a 6-gene focused bleeding panel and a 25-gene comprehensive bleeding panel are available. For more information see GNBLF / Bleeding Disorders, Focused Gene Panel, Next-Generation Sequencing, Varies or GNBLC / Bleeding Disorders, Comprehensive Gene Panel, Next-Generation Sequencing, Varies

 

Testing for the F8 gene as part of a customized panel is available. For more information see CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies.

 

Targeted testing for familial variants (also called site-specific or known variants testing) is available for the F8 gene. See FMTT / Familial Variant, Targeted Testing, Varies. To obtain more information about this testing option, call 800-533-1710.



Additional Testing Requirements


All prenatal specimens must be accompanied by a maternal blood specimen; order MATCC / Maternal Cell Contamination, Molecular Analysis, Varies on the maternal specimen as this must be a different order number than the prenatal specimen.



Shipping Instructions


Specimen preferred to arrive within 96 hours of collection.



Necessary Information


Hemophilia A Patient Information is required. Testing may proceed without the patient information, however, the information aids in providing a more thorough interpretation. Ordering providers are strongly encouraged to fill out the form and send with the specimen.



Specimen Required


Patient Preparation: A previous bone marrow transplant from an allogenic donor will interfere with testing. For instructions for testing patients who have received a bone marrow transplant, call 800-533-1710.

 

Submit only 1 of the following specimens:

 

Specimen Type: Whole blood

Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Yellow top (ACD)

Specimen Volume: 3 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send whole blood specimen in original tube. Do not aliquot.

Specimen Stability Information: Ambient (preferred) 4 days/Refrigerated

 

Prenatal Specimens

Due to its complexity, consultation with the laboratory is required for all prenatal testing; call 800-533-1710 to speak to a genetic counselor. 

 

Specimen Type: Amniotic fluid

Container/Tube: Amniotic fluid container

Specimen Volume: 20 mL

Specimen Stability Information: Refrigerated (preferred)/Ambient

Additional information:

1. A separate culture charge will be assessed under CULAF / Culture for Genetic Testing, Amniotic Fluid.

2. All prenatal specimens must be accompanied by a maternal blood specimen; order MATCC / Maternal Cell Contamination, Molecular Analysis, Varies on the maternal specimen.

 

Specimen Type: Chorionic villi

Container/Tube: 15-mL tube containing 15 mL of transport media

Specimen Volume: 20 mg

Specimen Stability Information: Refrigerated

Additional Information:

1. A separate culture charge will be assessed under CULFB / Fibroblast Culture for Biochemical or Molecular Testing.

2. All prenatal specimens must be accompanied by a maternal blood specimen; order MATCC / Maternal Cell Contamination, Molecular Analysis, Varies on the maternal specimen.

 

Acceptable:

Specimen Type: Confluent cultured cells

Container/Tube: T-25 flask

Specimen Volume: 2 Flasks

Collection Instructions: Submit confluent cultured cells from another laboratory.

Specimen Stability Information: Ambient (preferred)/Refrigerated

Additional Information:

All prenatal specimens must be accompanied by a maternal blood specimen; order MATCC / Maternal Cell Contamination, Molecular Analysis, Varies on the maternal specimen.


Forms

1. Hemophilia A Patient Information (T712) is required.

2. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing (Spanish) (T826)

3. If not ordering electronically, complete, print, and send an Coagulation Test Request (T753) with the specimen.

Useful For

Confirming a clinical diagnosis of hemophilia A in affected male patients with the identification of a disease-causing variant in the F8 gene

 

Determining the disease-causing alteration within the F8 gene to delineate the underlying molecular defect in a male patient with a laboratory diagnosis of hemophilia A

 

Identifying the causative alteration for prognostic and genetic counseling purposes

 

Assessing hemophilia A carrier status for female patients with a family history of hemophilia A

 

Prenatal testing for hemophilia A when a familial F8 variant has been previously identified in a family member

Disease States

  • Hemophilia A

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
CULFB Fibroblast Culture for Genetic Test Yes No
CULAF Amniotic Fluid Culture/Genetic Test Yes No
MATCC Maternal Cell Contamination, B Yes No

Method Name

Sequence Capture and Targeted Next-Generation Sequencing (NGS) followed by Polymerase Chain Reaction (PCR) and Sanger Sequencing

Reporting Name

F8 Gene, Full Gene NGS

Specimen Type

Varies

Specimen Minimum Volume

Blood: 1 mL; Amniotic fluid: 10 mL; Other specimen types: see Specimen Required

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Varies

Reject Due To

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Clinical Information

Hemophilia A is a hereditary bleeding disorder associated with germline variants in the F8 gene. It is inherited in an X-linked recessive manner with variable expressivity and is estimated to affect 1 in 4000-5000 live male births.(2)

 

Hemophilia A is characterized by a deficiency in clotting factor VIII (FVIII), an essential blood coagulation protein. Symptomatic male patients may experience mild to severe bleeding problems, including excessive bruising, prolonged epistaxis, post-operative bleeding, hemarthrosis, deep-muscle hematomas, and/or intracranial or gastrointestinal tract bleeding.(2,3) Female carriers are not typically affected but some may experience increased bleeding tendencies especially after medical procedures and surgery. Note that FVIII activity may not correlate with the severity of symptoms in females.(4-6)

 

Several causes of acquired (nongenetic) hemophilia A should be excluded prior to genetic testing, including heparin use, disorders associated with antibodies to clotting factors such as systemic lupus erythematosus or antiphospholipid syndrome, pregnancy and the postpartum period, rheumatic disease, solid and hematologic malignancies, and use of certain drugs (eg, penicillin, sulfamides, phenytoin, interferon, fludarabine).(7)

 

The World Federation of Hemophilia provides guidelines regarding diagnosis, management, and laboratory testing for individuals with hemophilia A.(8)

Reference Values

An interpretive report will be provided.

Day(s) Performed

Varies

Report Available

28 to 42 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

81407

88233-Tissue culture, skin, solid tissue biopsy (if appropriate)

88240-Cryopreservation (if appropriate)

88235-Amniotic fluid culture (if appropriate)

81265-Maternal cell contamination (if appropriate)