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HelpOrder Code F8INV Hemophilia A F8 Gene, Intron 1 and 22 Inversion Mutation Analysis, Whole Blood
Useful For
First-tier molecular testing for male patients affected with severe hemophilia A when a variant has not been identified in the family
Determining hemophilia A carrier status for at-risk female patients, ie, individuals with a family history of severe hemophilia A
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| MATCC | Maternal Cell Contamination, B | Yes | No |
Testing Algorithm
Maternal cell contamination testing will be performed for all cord blood specimens. A maternal whole blood sample with an order for MATCC / Maternal Cell Contamination, Molecular Analysis, Varies is also required to perform this test. See Additional Testing Requirements.
The following algorithms are available:
Special Instructions
Reporting Name
HA F8 Intron 1/22 Inversion, BSpecimen Type
Whole bloodOrdering Guidance
For evaluation of a patient with bleeding symptoms and no known personal history of a bleeding disorder, consider ALBLD / Bleeding Diathesis Profile, Limited, Plasma or the specific factor assays.
Additional Testing Requirements
Due to the complexity of testing non-peripheral blood, consultation with the laboratory is required for all cord blood samples. Order this test on the cord blood specimen (only 1 specimen tube required) and order MATCC / Maternal Cell Contamination, Molecular Analysis, Varies on the maternal specimen.
Necessary Information
Hemophilia A Patient Information(T712) 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. Call 800-533-1710 for instructions for testing patients who have received a bone marrow transplant.
Container/Tube:
Preferred: Lavender top (EDTA)
Acceptable: Yellow top (ACD) or blue top (3.2% sodium citrate)
Specimen Volume: 4 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Send whole blood specimen in original tube. Do not aliquot.
Specimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Whole blood | Ambient (preferred) | 7 days |
| Frozen | 7 days | |
| Refrigerated | 7 days |
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | OK |
Genetics Test Information
This test detects the common inversion variants within the F8 gene. Approximately 50% of affected male patients with severe hemophilia A have been shown to have an inversion.
It is recommended that the F8 inversion variant be confirmed in an affected male patient or obligate female carrier prior to testing at-risk individuals.
Method Description
Genomic DNA from whole blood or cord blood is digested with restriction enzyme, ligated with T4 DNA ligase, and amplified by polymerase chain reaction (PCR) with primers specific for the F8 intron 22 inversion variants.(Rosetti LC, Radic CP, Larripa IB, De Brasi CD: Developing a new generation of tests for genotyping hemophilia-causative rearrangements involving int22h and int1h hotspots in the factor VIII gene. J Thromb Haemost. 2008 May;6(5):830-836)
Genomic DNA from whole blood or cord blood is amplified by PCR with primers specific for the F8 intron 1 inversion mutation.(Bagnall RD, Waseem N, Green PM, Giannelli F: Recurrent inversion breaking intron 1 of the factor VIII gene is a frequent cause of severe hemophilia A. Blood 2002;99(1):168-174; Meijer P, Verbruggen, Spannagi M: Clotting factors and inhibitors: Assays and Interpretation. In: Kottke-Marchant K, ed. Laboratory Hematology Practice. Wiley Blackwell Publishing. 2012:435-446)
Day(s) Performed
Weekly
Performing Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
81403
Reference Values
An interpretive report will be provided.
Method Name
Polymerase Chain Reaction (PCR) or Inverse Shifting-Polymerase Chain Reaction (IS-PCR)
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 a Coagulation Test Request (T753) with the specimen.