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HelpTest ID GNFIB Congenital Fibrinogen Disorders, FGA, FGB, and FGG Genes, Next-Generation Sequencing, Varies
Ordering Guidance
This test is designed to detect single nucleotide and copy number variants in the FGA, FGB, and FGG genes associated with congenital fibrinogen disorders (CFD).
This test should only be considered if coagulation screening tests measuring thrombin clotting time (TT; with or without reptilase time), clottable fibrinogen, and fibrinogen antigen suggest a quantitative or functional defect in fibrinogen, especially if these findings are similar between family members.
For assessment of thrombin clotting time, order TTSC / Thrombin Time (Bovine), Plasma.
For assessment of fibrinogen function, order FIBTP / Fibrinogen, Plasma.
For assessment of fibrinogen quantity, order FIBAG / Fibrinogen Antigen, Plasma.
If genetic testing for CFD using a larger panel is desired, both a 25-gene comprehensive bleeding panel and a 16-gene comprehensive thrombosis panel are available. See GNBLC / Bleeding Disorders, Comprehensive Gene Panel, Next-Generation Sequencing, Varies; and GNTHR / Thrombosis Disorders, Comprehensive Gene Panel, Next-Generation Sequencing, Varies.
Customization of this panel and single gene analysis for any gene present on this panel are 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 genes on this panel. 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
Rare Coagulation Disorder 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
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. Rare Coagulation Disorder Patient Information (T824) 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
Evaluating congenital fibrinogen disorders (CFD) in patients with a personal or family history suggestive of a fibrinogen disorder
Confirming a CFD diagnosis with the identification of known or suspected disease-causing alterations in the FGA, FGB, or FGG genes
Determining the disease-causing alterations within the FGA, FGB, or FGG genes to delineate the underlying molecular defect in a patient with a laboratory diagnosis of suggestive of CFD
Identifying the causative alterations for genetic counseling purposes
Prognosis and risk assessment based on the genotype-phenotype correlations
Carrier testing for close family members of an individual with autosomal recessive afibrinogenemia/hypofibrinogenemia
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 |
Testing Algorithm
The clinical workup congenital fibrinogen disorders (CFD) should begin with global coagulation screening assays.
In afibrinogenemia, prothrombin time (PT), activated partial thromboplastin time (aPTT), thrombin clotting time (TT) may be infinitely prolonged.
In hypofibrinogenemia, TT is more sensitive than PT or aPTT for both quantitative and qualitative defects in fibrinogen. Reptilase time (RT) may be performed in addition to, or instead of, TT in specimens known, or suspected, to contain heparin, which artificially prolongs TT.
Further screening and identification of a mild fibrinogen deficiency or dysfibrinogenemia require a clottable fibrinogen assay (typically Clauss-method based) to assess fibrinogen function and an immunologic (antigenic) assay to assess fibrinogen quantity. Hypofibrinogenemia is indicated by a proportional reduction of both antigen and functional plasma fibrinogen concentrations. Dysfibrinogenemia is indicated by the combined presence of normal antigen amounts and reduced functional levels of circulating fibrinogen.(1-3)
Genetic testing for CFD is indicated if:
-Coagulation tests indicate a quantitative or functional defect in fibrinogen
-Acquired causes of fibrinogen disorders have been excluded (eg, liver disease, disseminated intravascular coagulopathy, trauma-induced coagulopathy, medications such as L-asparaginase, multiple myeloma or other malignancy, the use of plasma exchange using albumin as a replacement fluid, rheumatoid arthritis, systemic lupus erythematosus)
For prenatal specimens only:
-If amniotic fluid (nonconfluent cultured cells) is received, amniotic fluid culture/genetic test will be added at an additional charge.
-If chorionic villus specimen (nonconfluent cultured cells) is received, fibroblast culture for genetic test will be added at an additional charge.
For any prenatal specimen that is received, maternal cell contamination testing will be performed at an additional charge.
Special Instructions
Method Name
Sequence Capture and Targeted Next-Generation Sequencing (NGS) followed by Polymerase Chain Reaction (PCR) and Sanger Sequencing
Reporting Name
FGA/B/G Genes, Full Gene NGSSpecimen Type
VariesSpecimen 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 | ||
Reference Values
An interpretive report will be provided.
Day(s) Performed
Varies
Report Available
28 to 42 daysPerforming 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
81479
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)
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| GNFIB | FGA/B/G Genes, Full Gene NGS | 92992-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 619160 | Test Description | 62364-5 |
| 619161 | Specimen | 31208-2 |
| 619162 | Source | 31208-2 |
| 619163 | Result Summary | 50397-9 |
| 619164 | Result | 82939-0 |
| 619165 | Interpretation | 59465-5 |
| 619166 | Additional Results | 82939-0 |
| 619167 | Resources | 99622-3 |
| 619168 | Additional Information | 48767-8 |
| 619169 | Method | 85069-3 |
| 619170 | Genes Analyzed | 82939-0 |
| 619171 | Disclaimer | 62364-5 |
| 619172 | Released By | 18771-6 |