Hemophilia A F8 Gene, Intron 22 Inversion Known Mutation, Blood
Use
This test is primarily used for determining carrier status or diagnosing hemophilia A in individuals with a family history of severe hemophilia A due to an F8 intron 22 inversion mutation. It is especially useful for male patients affected with severe hemophilia A when a familial intron 22 inversion has been previously identified. The test detects the intron 22 inversion within the F8 gene, which accounts for approximately 45% of variants associated with severe hemophilia A. The analysis can only be performed when an intron 22 inversion has already been identified in the family, making it critical for families known to carry this mutation.
Special Instructions
Consultation with a genetic counselor or the laboratory is advised for postnatal umbilical cord blood specimens. All postnatal umbilical cord specimens must be accompanied by a maternal blood specimen for maternal cell contamination studies. Submit the Hemophilia A Patient Information form along with the specimen to provide a thorough interpretation. For New York clients, informed consent is required and must be documented. Consider the potential for germline mosaicism when interpreting negative results in mothers of affected individuals.
Limitations
This assay is specific for detecting F8 intron 22 inversion variants, and a negative result does not exclude the presence of other mutations in the F8 gene. Thus, the test may be uninformative if the family mutation has not been identified previously. Errors in result interpretation may occur if inaccurate or incomplete family and clinical histories are provided. Approximately 20% of mothers of isolated hemophilia A cases do not carry the F8 variant due to de novo mutation occurrence. The test does not substitute for full genetic counseling and evaluation.
New York Approved
Methodology
PCR-based (IS-PCR)
Biomarkers
LOINC Codes
- 91679-1
- 91679-1
- 42349-1
- 69047-9
- 18771-6
Result Turnaround Time
14-21 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
4 mL
Minimum Volume
1 mL
Container
Lavender top (EDTA); Yellow top (ACD) or blue top (3.2% sodium citrate) acceptable
Collection Instructions
Invert several times to mix blood. Send whole blood specimen in original tube. Do not aliquot. Whole blood collected postnatal from an umbilical cord is also acceptable if approved by the laboratory.
Patient Preparation
A previous bone marrow transplant from an allogeneic donor will interfere with testing.
Causes for Rejection
Gross lipemia OK; Gross hemolysis OK
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 7 days |
| Frozen | 7 days |