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Test Code GNF7 Factor VII Deficiency, F7 Gene, Next-Generation Sequencing, Varies


Ordering Guidance


Special coagulation testing for factor VII (FVII) activity should be performed prior to any genetic testing. For assessment of FVII activity, order F_7 / Coagulation Factor VII Activity Assay, Plasma.

 

This test should only be considered if clinical and family history, initial coagulation screens, and/or initial activity tests indicate a diagnosis of FVII deficiency (see Testing Algorithm).

 

If genetic testing for hereditary bleeding disorders using a larger panel is desired, both a 6-gene focused bleeding panel and a 25-gene comprehensive bleeding panel are available. For more information see GNBLF / Bleeding Disorders, Focused Gene Panel, Next-Generation Sequencing, Varies or GNBLC / Bleeding Disorders, Comprehensive Gene Panel, Next-Generation Sequencing, Varies.

 

Testing for the F7 gene as part of a customized panel is 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 mutations testing) is available for the F7 gene. 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

 

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)/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 factor VII deficiency (FVIID) in patients with a personal or family history suggestive of FVIID

 

Confirming an FVIID diagnosis with the identification of known or suspected disease-causing alterations in the F7 gene

 

Determining the disease-causing alterations within the F7 gene to delineate the underlying molecular defect in a patient with a laboratory diagnosis of FVIID

 

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 a diagnosis of FVIID

Genetics Test Information

This test utilizes next-generation sequencing to detect single nucleotide and copy number variants in the F7 gene associated with factor VII deficiency (FVIID), a rare bleeding disorder. See Method Description for additional details.

 

Identification of a disease-causing variant may assist with diagnosis, prognosis, clinical management, recurrence risk assessment, familial screening, and genetic counseling for FVIID.

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 for factor VII deficiency (FVIID) should begin with special coagulation testing for factor VII (FVII) activity.

 

Genetic testing for F7D is indicated if:

-FVII activity is less than 65% of normal (Note: reference range may vary depending on the locally established reference range)

-Acquired causes of F7D have been excluded (eg, vitamin K deficiency, use of vitamin K antagonists such as warfarin, liver disease, sepsis)

 

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.

Method Name

Sequence Capture and Targeted Next-Generation Sequencing (NGS) followed by Polymerase Chain Reaction (PCR) and Sanger Sequencing

Reporting Name

F7 Gene, Full Gene NGS

Specimen Type

Varies

Specimen Minimum Volume

Whole blood: 1 mL; Amniotic fluid: 10 mL; Other specimen types: See Specimen Required

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Varies

Reject Due To

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Clinical Information

Factor VII deficiency (FVIID) is a rare hereditary bleeding disorder associated with germline variants in the F7 gene. It is inherited in an autosomal recessive manner with variable expressivity; both male and female individuals may be affected. The estimated prevalence is 1 in 500,000 individuals.(1)

 

FVIID is characterized by a deficiency or reduced activity of clotting factor VII. The symptoms and severity of FVIID are highly variable. Individuals with mild disease do not typically experience spontaneous bleeding but may have prolonged bleeding after trauma or surgery. For those with severe disease, symptoms include epistaxis, menorrhagia, easy bruising, gum bleeding, and post-surgical bleeding. Onset can occur within the first 6 months of life and include life-threatening intracranial and gastrointestinal hemorrhages. Joint and muscle bleeds are less common. FVIID does not protect against venous thromboembolism.(2-4)

 

In many cases of FVIID, there is no consistent correlation between FVII plasma levels and disease severity.(1,4,5) However, good correlation has been demonstrated between FVII levels and genotype. Individuals with homozygous or compound heterozygous disease-causing variants in the F7 gene have been found to have significantly lower FVII levels than those individuals with heterozygous or no detectable F7 variants.(6)

 

Causes of acquired (nongenetic) FVIID should be excluded prior to genetic testing, including vitamin K deficiency, use of vitamin K antagonists such as warfarin, liver disease, and sepsis.(7,8)

 

The United Kingdom Haemophilia Centre Doctors' Organization provides guidelines regarding diagnosis and management for individuals with inherited bleeding disorders, including F7D.(9)

Reference Values

An interpretive report will be provided.

Interpretation

All detected variants are evaluated according to American College of Medical Genetics and Genomics recommendations.(10) Variants are classified based on known, predicted, or possible pathogenicity and reported with interpretive comments detailing their potential or known significance.

Day(s) Performed

Varies

Report Available

28 to 42 days

Specimen Retention Time

Whole blood: 2 weeks (if available); Extracted DNA: 3 months; Amniotic fluid, cultured amniocytes, chorionic villi, cultured chorionic villi: 1 month

Performing 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)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
GNF7 F7 Gene, Full Gene NGS 94235-9

 

Result ID Test Result Name Result LOINC Value
619090 Test Description 62364-5
619091 Specimen 31208-2
619092 Source 31208-2
619093 Result Summary 50397-9
619094 Result 82939-0
619095 Interpretation 59465-5
619096 Additional Results 82939-0
619097 Resources 99622-3
619098 Additional Information 48767-8
619099 Method 85069-3
619100 Genes Analyzed 82939-0
619101 Disclaimer 62364-5
619102 Released By 18771-6