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HelpOrder Code F81B Hemophilia A F8 Gene, Intron 1 Inversion Known Mutation, Whole Blood
Useful For
First-tier molecular testing for male patients affected with severe hemophilia A, when a familial intron 1 inversion has been previously identified
Determining hemophilia A carrier status for at-risk female patients, ie, individuals with a family history of severe hemophilia A due to F8 intron 1 inversion
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, Blood is required to perform this test. See Additional Testing Requirements.
The following algorithms are available:
Special Instructions
Reporting Name
HA F8 Intron 1 Inversion KM, BSpecimen Type
Whole bloodOrdering Guidance
If a familial variant has not been identified in a severely affected hemophilia A patient, order F8INV / Hemophilia A F8 Gene, Intron 1 and 22 Inversion Mutation Analysis, Whole Blood.
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 nonperipheral 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, Blood 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 | Special Container |
|---|---|---|---|
| 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 intron 1 inversion in the F8 gene. The intron 1 inversion variant accounts for approximately 5% of the variants associated with severe hemophilia A.
Intron 1 inversion known variant analysis can only be performed for individuals when an intron 1 inversion has already been identified in the family. For testing options, see Ordering Guidance.
Reference Values
An interpretive report will be provided.
Method Description
Genomic DNA from whole blood or cord blood is amplified by polymerase chain reaction with primers specific for the F8 intron 1 inversion variant.(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 Jan;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
Method Name
Polymerase Chain Reaction (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.