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HelpTest Code BTKSG Bruton Tyrosine Kinase, BTK Full Gene Analysis, Varies
Ordering Guidance
Targeted testing for familial variants (also called site-specific or known variants testing) is available for variants identified in the BTK gene. See FMTT / Familial Variant, Targeted Testing, Varies. To obtain more information about testing option, call 800-533-1710.
Additional Testing Requirements
To confirm a diagnosis of X-linked agammaglobulinemia in male patients, the preferred approach is to order this test concurrently with BTK / Bruton Tyrosine Kinase, Protein Expression, Flow Cytometry, Blood.
Shipping Instructions
Specimen preferred to arrive within 96 hours of collection.
Necessary Information
Bruton Tyrosine Kinase (BTK) Gene Sequencing Patient Information form (T620) is highly recommended. Testing may proceed without the patient information. However, it aids in providing a more thorough interpretation. Ordering providers are strongly encouraged to complete the form and send it 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) or yellow top (ACD)
Acceptable: Any anticoagulant
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 for Biochemical or Molecular Testing. An additional 3 to 4 weeks is required to culture fibroblasts before genetic testing can occur.
Forms
1. 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)
2. Bruton Tyrosine Kinase (BTK) Gene Sequencing Patient Information form (T620)
Secondary ID
619760Useful For
Confirming a diagnosis of X-linked agammaglobulinemia in patients with a history of recurrent sinopulmonary infections, profound hypogammaglobulinemia, and less than 1% peripheral B cells, with or without abnormal Bruton tyrosine kinase (BTK) protein expression by flow cytometry
Evaluating for the presence of BTK variants in family members of affected individuals, including those who do not demonstrate carrier phenotype by BTK flow cytometry
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| CULFB | Fibroblast Culture for Genetic Test | Yes | No |
Testing Algorithm
For skin biopsy or cultured fibroblast specimens, fibroblast culture 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
Specimen Type
VariesSpecimen Minimum Volume
Blood: 1 mL; Skin biopsy or cultured fibroblasts: 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.
Interpretation
All detected variants are evaluated according to American College of Medical Genetics and Genomics recommendations.(4) Variants are classified based on known, predicted, or possible pathogenicity and reported with interpretive comments detailing their potential or known significance.
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 BTK gene, 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), and 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 BTK gene.
There may be regions of BTK 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.(Unpublished Mayo method)
Confirmation of select reportable variants may be performed by alternate methodologies based on internal laboratory criteria.
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.
|
Gene symbol |
Reference transcript |
Additional evaluations |
Technical limitations |
|
BTK |
NM_000061.2 |
c.-193A>G |
- |
Day(s) Performed
Varies
Report Available
28 to 42 daysSpecimen Retention Time
Whole blood: 2 weeks (if available); Extracted DNA: 3 months; Cultured fibroblasts, skin biopsy: 1 monthPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
81406
88233- Tissue culture, skin, solid tissue biopsy (if appropriate)
88240- Cryopreservation (if appropriate)
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| BTKSG | BTK Gene, Full Gene Analysis | 94241-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 619761 | Test Description | 62364-5 |
| 619762 | Specimen | 31208-2 |
| 619763 | Source | 31208-2 |
| 619764 | Result Summary | 50397-9 |
| 619765 | Result | 82939-0 |
| 619766 | Interpretation | 69047-9 |
| 619767 | Additional Results | 82939-0 |
| 619768 | Resources | 99622-3 |
| 619769 | Additional Information | 48767-8 |
| 619770 | Method | 85069-3 |
| 619771 | Genes Analyzed | 82939-0 |
| 619772 | Disclaimer | 62364-5 |
| 619773 | Released By | 18771-6 |