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Test Code UBA1Q UBA1 Mutation Quantitative Detection, VEXAS syndrome, Droplet Digital PCR, Varies


Ordering Guidance


This test is intended for patients with clinical symptoms and other pertinent laboratory findings raising concern for VEXAS syndrome. These may include, but are not limited to, systemic or localized (eg, ear, orbital, skin) tissue inflammation presenting as rheumatologic disease, abnormal (usually low) whole blood counts, macrocytic anemia, characteristic microscopic changes in the bone marrow, as well as others.



Shipping Instructions


1. Both refrigerated and ambient specimens must arrive within 7 days of collection.

2. Collect and package specimen as close to shipping time as possible.



Necessary Information


The following information is required:

1. Pertinent clinical history

2. Date of collection

3. Specimen source (blood or bone marrow)



Specimen Required


Submit only 1 of the following specimens:

 

Specimen Type: Whole blood

Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Yellow top (ACD-B) or green top (heparin)

Specimen Volume: 4 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send whole blood specimen in original tube. Do not aliquot.

3. Label specimen as blood.

Specimen Stability: Refrigerated 7 days/Ambient 7 days

 

Specimen Type: Bone marrow aspirate

Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Yellow top (ACD-B) or green top (heparin)

Specimen Volume: 2 mL

Collection Instructions:

1. Invert several times to mix bone marrow.

2. Send bone marrow specimen in original tube. Do not aliquot.

3. Label specimen as bone marrow.

Specimen Stability: Refrigerated 7 days/Ambient 7 days

 

Specimen Type: Extracted DNA from blood or bone marrow

Container/Tube: 1.5- to 2-mL tube with indication of volume and concentration of DNA

Specimen Volume: Entire specimen

Collection Instructions:

1. Label specimen as extracted DNA and source of specimen

2. Indicate volume and concentration of DNA on label. The required volume of DNA is at least 50 mcL at a concentration of 50 ng/mcL

Specimen Stability: Frozen (preferred)/Refrigerated


Forms

1. Hematopathology Patient Information (T676)

2. If not ordering electronically, complete, print, and send a Hematopathology/Cytogenetics Test Request (T726) with the specimen.

Secondary ID

620900

Useful For

Identification of pathogenic variant(s) in the UBA1 gene in patients presenting with symptoms concerning for or consistent with VEXAS syndrome

Method Name

Droplet Digital Polymerase Chain Reaction

Specimen Type

Varies

Specimen Minimum Volume

Whole blood: 4 mL
Bone marrow: 2 mL
Extracted DNA: 50 mcL at 50 ng/mcL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Refrigerated (preferred) 7 days
  Ambient  7 days

Reject Due To

Gross hemolysis Reject
Moderately to severely clotted Reject

Reference Values

An interpretive report will be provided.

Interpretation

The assay is reported as positive or negative. In positive cases, the mutation type and its variant allele fraction (VAF) are reported.

 

VAF%= (mutant copy number)/(mutant copy number + wild-type number)

 

The precision of this quantitative assay is very high but inter-assay variability may occur such that quantitative changes should not be considered significant if 2 single measurements differ by less than 0.5 log (3.16-fold).

Method Description

This test is performed using a droplet digital polymerase chain reaction (ddPCR) system. DNA extracted from patient samples is PCR-amplified using oligonucleotide primers and mutant- and wildtype-specific fluorescently labeled probes directed to the genomic target regions. Results are analyzed using dedicated software and Poisson statistics to provide absolute quantification of mutant target and wild type copies. Calculated results are reported as mutant fractional abundance (variant allele fraction %).(Unpublished Mayo method)

Day(s) Performed

Monday through Saturday

Report Available

4 to 8 days

Specimen Retention Time

Whole blood/bone marrow: 2 weeks; Extracted DNA: 3 months

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

81479

LOINC Code Information

Test ID Test Order Name Order LOINC Value
UBA1Q UBA1 Mutation, Quant, ddPCR, V 104268-8

 

Result ID Test Result Name Result LOINC Value
MP086 Specimen Type 31208-2
620938 Interpretation 59465-5
620939 Signing Pathologist 19139-5