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Test Code GNADM Hereditary Thrombotic Thrombocytopenic Purpura, ADAMTS13 Gene, Next-Generation Sequencing, Varies


Ordering Guidance


This test is designed to detect disease-causing variants in the ADAMTS13 gene and to be utilized for genetic confirmation of a clinical diagnosis of hereditary thrombotic thrombocytopenic purpura (TTP). Genetic testing for hereditary TTP should only be considered if a patient’s clinical presentation and initial ADAMTS-13 activity and functional inhibitor screens indicate a diagnosis.

 

This test does not measure ADAMTS-13 activity or the presence/absence of inhibitors. For assessment of ADAMTS-13 activity and inhibitor status, order ADM13 / ADAMTS13 Activity and Inhibitor Profile, Plasma.

 

Testing for the ADAMTS13 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 variants testing) is available for the ADAMTS13 gene. See FMTT / Familial Variant, Targeted Testing, Varies. To obtain more information about this testing option, call 800-533-1710.



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 it with the specimen.



Specimen Required


Specimen Type: Whole blood

Patient Preparation: A previous bone marrow transplant from an allogenic donor will interfere with testing. Call 800-533-1710 for instructions for testing patients who have received a bone marrow transplant.

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


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)

Useful For

Evaluating hereditary thrombotic thrombocytopenic purpura (TTP) in patients with a personal or family history suggestive of thrombotic microangiopathy

 

Confirming a hereditary TTP diagnosis with the identification of known or suspected disease-causing alteration(s) in the ADAMTS13 gene

 

Determining the disease-causing alterations within the ADAMTS13 gene to delineate the underlying molecular defect in a patient with a laboratory diagnosis of hereditary TTP

 

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 hereditary TTP

 

This test is not intended for prenatal diagnosis.

Testing Algorithm

The clinical workup for hereditary thrombotic thrombocytopenic purpura (TTP)  should begin with a plasma ADAMTS-13 (a disintegrin and metalloprotease with thrombospondin type 1 motif 13 repeats) activity assay performed on a specimen collected before initiation of plasma therapy.

 

Clinical scoring systems, such as the PLASMIC score, may assist in providing guidance for the necessity of ADAMTS-13 activity testing.(1)

 

Genetic testing for hereditary TTP is indicated if:

-ADAMTS-13 activity is less than 10% and a functional inhibitor screen as measured by the Bethesda assay is negative (defined as less than 0.4 Bethesda units)

-Non-TTP medical conditions that may be associated with severe ADAMTS-13 deficiency (≤10%) have been excluded, eg, hemolytic uremic syndrome, hematopoietic stem cell and solid-organ transplantation, liver disease, disseminated intravascular coagulation, malignancy, viral infection (eg, HIV), sepsis, pregnancy (preeclampsia/eclampsia or HELLP [hemolysis, elevated liver enzymes and low platelets] syndrome), and medications, such as antiplatelet agents, calcineurin inhibitors, and certain chemotherapeutics

 

International expert groups have provided recommendations on best practices for ADAMTS-13 assays in clinical laboratories and established testing algorithms for the identification of TTP.(2,3)

Method Name

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

Reporting Name

ADAMTS13 Gene, Full Gene NGS

Specimen Type

Varies

Specimen Minimum Volume

1 mL

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 days

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

LOINC Code Information

Test ID Test Order Name Order LOINC Value
GNADM ADAMTS13 Gene, Full Gene NGS 99960-7

 

Result ID Test Result Name Result LOINC Value
619230 Test Description 62364-5
619231 Specimen 31208-2
619232 Source 31208-2
619233 Result Summary 50397-9
619234 Result 82939-0
619235 Interpretation 69047-9
619236 Additional Results 82939-0
619237 Resources 99622-3
619238 Additional Information 48767-8
619239 Method 85069-3
619240 Genes Analyzed 82939-0
619241 Disclaimer 62364-5
619242 Released By 18771-6