Test Catalog

Test ID: FIBNG    
Congenital Fibrinogen Disorders, FGA, FGB, and FGG Genes, Next-Generation Sequencing, Varies

Useful For Suggests clinical disorders or settings where the test may be helpful

Genetic confirmation of congenital disorders of fibrinogen with the identification of an alteration in FGA, FGB, or FGG that is known or suspected to cause disease


Testing for close family members of an individual with a diagnosis of afibrinogenemia/hypofibrinogenemia or dysfibrinogenemia/hypodysfibrinogenemia


This test is not intended for prenatal diagnosis

Genetics Test Information Provides information that may help with selection of the correct genetic test or proper submission of the test request

This test detects pathogenic alterations within the FGA, FGB, and FGG genes to delineate the underlying molecular defect in a patient with a laboratory diagnosis of congenital afibrinogenemia/hypofibrinogenemia or dysfibrinogenemia/hypodysfibrinogenemia.


The gene targets for this test are:

Gene name (transcript): FGA (GRCh37 [hg19] NM_021871)

Chromosomal location: 4q31.3


Gene name (transcript): FGB (GRCh37 [hg19] NM_005141)

Chromosomal location: 4q31.3


Gene name (transcript): FGG (GRCh37 [hg19] NM_000509)

Chromosomal location: 4q32.1

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

The laboratory workup for a congenital fibrinogen disorder begins with global coagulation screening assays.


In afibrinogenemia, prothrombin time (PT), activated partial thromboplastin time (aPTT), and thrombin clotting time (TT) may be infinitely prolonged in afibrinogenemia.


In hypofibrinogenemia, TT is more sensitive than PT or aPTT for both quantitative and qualitative defects in fibrinogen.(1) Reptilase time (RT) maybe performed in addition to or instead of TT in samples known or suspected to contain heparin, which artificially prolongs TT.


PT, aPTT, and TT have poor sensitivity for mild fibrinogen deficiency or dysfunction. Further screening and identification of a mild fibrinogen deficiency or dysfibrinogenemia requires a clottable fibrinogen assay (typically Clauss-method based, eg, FIBTP / Fibrinogen, Plasma) to further test fibrinogen function as well as an immunologic (antigentic) assay (FIBAG / Fibrinogen Antigen, Plasma) to detect the quantity of fibrinogen present. Hypofibrinogenemia is indicated by a proportional decrease of functional and immunoreactive fibrinogen. Dysfibrinogenemia is indicated by a discrepancy between functional and immunoreactive fibrinogen.


Genetic testing for a congenital disorder of fibrinogen is indicated if:

-Coagulation tests indicate a quantitative or functional defect in fibrinogen

-Acquired causes of fibrinogen deficiency or dysfunction have been excluded (eg, thrombin clotting time [TT] may be prolonged by the presence of heparin, prior exposure to bovine thrombin, and high concentrations of serum proteins, as in multiple myeloma)

Special Instructions Library of PDFs including pertinent information and forms related to the test

Method Name A short description of the method used to perform the test

Custom Sequence Capture and Targeted Next-Generation Sequencing (NGS) Followed by Polymerase Chain Reaction (PCR) and Sanger Sequencing When Appropriate

NY State Available Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name Lists a shorter or abbreviated version of the Published Name for a test

FGA/B/G Genes, Full Gene NGS

Aliases Lists additional common names for a test, as an aid in searching

Bleeding diathesis
Abnormal bleeding
Fibrinogen deficiency
Fibrinogen Disorder
Fibrinogen storage disease