Order Code GNMTC Macro/Microthrombocytopenia Gene Panel, Next-Generation Sequencing, Varies

Ordering Guidance

This test is designed to evaluate a variety of hereditary macro- or microthrombocytopenia disorders and to be utilized for genetic confirmation of a phenotypic diagnosis of a macro- or microthrombocytopenia disorder.

If testing for hereditary platelet disorders using a larger, comprehensive panel is desired, a 70-gene platelet panel is available; order GNPLT / Platelet Disorders, Comprehensive Gene Panel, Next-Generation Sequencing, Varies.

This test is not designed to evaluate for hereditary bleeding disorders. For patients with clinical suspicion of an inherited bleeding disorder, it is important to exclude plasmatic factor deficiencies (eg, von Willebrand disease, hemophilia, or other factor deficiencies) prior to considering an inherited platelet function defect. If bleeding is the indication for testing and testing for hereditary bleeding disorders is desired, bleeding panels 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.

For assessment of hereditary platelet disorders that have ultrastructural abnormalities, such as gray platelet syndrome, order PTEM / Platelet Transmission Electron Microscopic Study, Whole Blood.

For assessment of hereditary platelet disorders due to quantitative surface glycoprotein deficiencies, order PLAFL / Platelet Glycoprotein Flow Platelet Surface Glycoprotein by Flow Cytometry, Blood.

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 mutations 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.

Shipping Instructions

Specimen preferred to arrive within 96 hours of collection.

Necessary Information

Platelet Esoteric Testing 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. Call 800-533-1710 for instructions for testing patients who have received a bone marrow transplant.

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

Specimen Type: Skin biopsy

Supplies: Fibroblast Biopsy Transport Media (T115)

Container/Tube: Sterile container with any standard cell culture media (eg, minimal essential media, RPMI 1640). The solution should be supplemented with 1% penicillin and streptomycin.

Specimen Volume: 4-mm punch

Specimen Stability Information: Refrigerated (preferred)/Ambient

Additional Information: A separate culture charge will be assessed under CULFB / Fibroblast Culture for Biochemical or Molecular Testing. An additional 3 to 4 weeks is required to culture fibroblasts before genetic testing can occur.

Specimen Type: Cultured fibroblasts

Container/Tube: T-25 flask

Specimen Volume: 2 flasks

Collection Instructions: Submit confluent cultured fibroblast cells from a skin biopsy from another laboratory. Cultured cells from a prenatal specimen will not be accepted.

Specimen Stability Information: Ambient (preferred)/Refrigerated (<24 hours)

Additional Information: A separate culture charge will be assessed under CULFB / Fibroblast Culture Biochemical or Molecular Testing. An additional 3 to 4 weeks is required to culture fibroblasts before genetic testing can occur.

Forms

1. Platelet Esoteric Testing Patient Information 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 macro- or microthrombocytopenia disorders in patients with a personal or family history suggestive of a hereditary macro- or microthrombocytopenia disorder

Diagnosing hereditary macro- or microthrombocytopenia disorders for patients in whom phenotypic testing is non-diagnostic but there is a strong clinical suspicion of the hereditary macro- or microthrombocytopenia disorder

Confirming a hereditary macro- or microthrombocytopenia disorder diagnosis with the identification of a known or suspected disease-causing alteration in one or more of 20 genes associated with a variety of hereditary macro- or microthrombocytopenia disorders

Determining the disease-causing alterations within one or more of these 20 genes to delineate the underlying molecular defect in a patient with a laboratory diagnosis of a macro- or microthrombocytopenia disorder

Identifying the causative alteration for genetic counseling purposes

Prognosis and risk assessment based on the genotype-phenotype correlations

Providing a prognosis in syndromic hereditary macro- or microthrombocytopenia disorders

Carrier testing for close family members of an individual with a hereditary macro- or microthrombocytopenia disorder diagnosis

This test is not intended for prenatal diagnosis

Genetics Test Information

This test utilizes next-generation sequencing to detect single nucleotide and copy number variants in 20 genes associated with a variety of macrothrombocytopenia and microthrombocytopenia disorders: ABCG5, ABCG8, ACTN1, ARPC1B, CDC42, DIAPH1, FLNA, FYB1, GATA1, GNE, GP1BA, GP1BB, GP9, MPIG6B, MYH9, PRKACG, SLFN14, TPM4, TUBB1, and WAS. See Targeted Genes and Methodology Details for Macro/Microthrombocytopenia Gene Panel and 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 a variety of macrothrombocytopenia and microthrombocytopenia disorders.

Reflex Tests

Test ID	Reporting Name	Available Separately	Always Performed
CULFB	Fibroblast Culture for Genetic Test	Yes	No

Testing Algorithm

The clinical workup for detecting inherited platelet disorders should begin with a careful review of complete blood cell count and peripheral blood smear results as well as other platelet tests, such as light transmission platelet aggregometry, electrical impedance whole blood aggregometry, platelet function analyzer 100, platelet transmission electron microscopy (TEM), and platelet flow cytometric analysis. TEM is an essential tool for laboratory diagnosis of various hereditary platelet disorders that have ultrastructural abnormalities, such as gray platelet syndrome. Flow cytometry is the preferred method to assess hereditary platelet disorders due to quantitative surface glycoprotein deficiencies.

Platelet laboratory testing may not be able to identify all inherited platelet disorders. Occasionally, the clinical picture may be consistent with a defect in primary hemostasis, but the results of platelet function tests may be normal or non-diagnostic.

Genetic testing for hereditary platelet disorders is indicated if:

-Platelet tests indicate a deficiency or functional abnormality

-There is a clinical suspicion for a hereditary platelet disorder due to family history or patientâ€™s clinical presentation

-Acquired causes of deficiencies associated with platelet disorders have been excluded

If a platelet disorder is a concern, a set of clinical guidelines from the British Society for Haematology on testing for heritable platelet disorders is freely available.(1)

For skin biopsy or cultured fibroblast specimens:

For skin biopsy or cultured fibroblast specimens, fibroblast culture testing will be performed at an additional charge. If viable cells are not obtained, the client will be notified.

Special Instructions

Method Name

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

Reporting Name

Macrothrombocytopenia Panel, NGS

Specimen Type

Varies

Specimen Minimum Volume

Blood: 1 mL; Cultured fibroblasts/skin biopsy: 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.

Reference Values

An interpretive report will be provided.

Method Description

Next-generation sequencing (NGS) and/or Sanger sequencing are performed to test for the presence of variants in coding regions and intron/exon boundaries of the genes analyzed, as well as some other regions that have known disease-causing variants. The human genome reference GRCh37/hg19 build was used for sequence read alignment. At least 99% of the bases are covered at a read depth over 30X. Sensitivity is estimated at above 99% for single nucleotide variants, above 94% for deletions-insertions (delins) less than 40 base pairs (bp), above 95% for deletions up to 75 bp, and insertions up to 47 bp. NGS and/or a polymerase chain reaction-based quantitative method is performed to test for the presence of deletions and duplications in the genes analyzed.

There may be regions of genes that cannot be effectively evaluated by sequencing or deletion and duplication analysis as a result of technical limitations of the assay, including regions of homology, high guanine-cytosine (GC) content, and repetitive sequences. See Targeted Genes and Methodology Details for Macro/Microthrombocytopenia Gene Panel and Methodology Details for details regarding the targeted genes analyzed for each test and specific gene regions not routinely covered.((Unpublished Mayo method)

Reference transcript numbers may be updated due to transcript re-versioning. Always refer to the final patient report for gene transcript information referenced at the time of testing. Confirmation of select reportable variants may be performed by alternate methodologies based on internal laboratory criteria.

Genes analyzed: ABCG5, ABCG8, ACTN1, ARPC1B, CDC42, DIAPH1, FLNA, FYB1, GATA1, GNE, GP1BA, GP1BB, GP9, MPIG6B, MYH9, PRKACG, SLFN14, TPM4, TUBB1, and WAS

Day(s) Performed