Home
HelpTest Code 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.
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 both the prenatal specimen and the maternal specimen as separate order numbers.
Shipping Instructions
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 healthcare professionals 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 whole blood testing. For information about 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 4 days
Additional Information: To ensure minimum volume and concentration of DNA are met, the requested volume must be submitted. Testing may be canceled if DNA requirements are inadequate.
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) 24 hours/Ambient 24 hours
Additional information:
1. Specimens are preferred to be received within 24 hours of collection. Culture and extraction will be attempted for specimens received after 24 hours and will be evaluated to determine if testing may proceed.
2. A separate culture charge will be assessed under CULAF / Culture for Genetic Testing, Amniotic Fluid. An additional 2 to 3 weeks are required to culture amniotic fluid before genetic testing can occur.
3. 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 24 hours
Additional Information:
1. Specimens are preferred to be received within 24 hours of collection. Culture and extraction will be attempted for specimens received after 24 hours and will be evaluated to determine if testing may proceed.
2. A separate culture charge will be assessed under CULFB / Fibroblast Culture for Biochemical or Molecular Testing. An additional 2 to 3 weeks are required to culture amniotic fluid before genetic testing can occur.
3. 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 Full flasks
Collection Instructions: Submit confluent cultured cells from another laboratory.
Specimen Stability Information: Ambient (preferred) 24 hours/Refrigerated 24 hours
Additional Information:
1. Specimens are preferred to be received within 24 hours of collection. Culture and extraction will be attempted for specimens received after 24 hours and will be evaluated to determine if testing may proceed.
2. A separate culture charge will be assessed under CULFB / Fibroblast Culture for Biochemical or Molecular Testing.
3. 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 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 |
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 |
|---|---|---|
| Varies | Varies | |
Reject Due To
All specimens will be evaluated by Mayo Clinic Laboratories for test suitability.Clinical Information
Congenital fibrinogen disorders (CFD) are rare bleeding abnormalities associated with germline variants in the FGA, FGB, and FGG genes. They manifest as one of 2 broad subtypes: autosomal recessive afibrinogenemia/hypofibrinogenemia (also known as a type I fibrinogen defect) or autosomal dominant dysfibrinogenemia (also known as a type II defect).
Afibrinogenemia and hypofibrinogenemia are considered quantitative defects characterized by undetectable or low levels of fibrinogen, respectively. Afibrinogenemia often presents in the neonatal period as umbilical cord bleeding. However, a later age of onset is not unusual and bleeding in the skin, oral cavity, gastrointestinal tract, genitourinary tract, and the central nervous system can occur. Individuals with hypofibrinogenemia are typically asymptomatic due to fibrinogen levels that, while lower than normal, are adequate to protect against spontaneous bleeding.
Dysfibrinogenemia is considered a qualitative defect. It is caused by structural changes in fibrinogen that modify its function, resulting in impaired clotting ability. Individuals with dysfibrinogenemia are commonly asymptomatic or have episodic symptoms. Cases are frequently discovered incidentally during routine coagulation testing or because of a positive family history.
Patients with CFD can also present with thrombotic events. Affected women are at increased risk of obstetric complications, including pregnancy loss, placental abruption, and postpartum hemorrhage.(3-6)
Causes of acquired (nongenetic) fibrinogen disorders should be excluded prior to genetic testing, including liver disease, consumptive coagulopathy (eg, disseminated intravascular coagulopathy, trauma-induced coagulopathy, medications (eg, L-asparaginase), malignancy (eg, multiple myeloma), the use of plasma exchange using albumin as a replacement fluid, and autoimmune conditions resulting in antifibrinogen antibodies (e.g., rheumatoid arthritis and systemic lupus erythematosus).(3,4)
The United Kingdom Haemophilia Centre Doctors' Organization provides guidelines regarding diagnosis and management for individuals with inherited bleeding disorders including fibrinogen deficiency.(7)
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)