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Test Code LRBA Lipopolysaccharide-Responsive Beige-Like Anchor Protein (LRBA) Deficiency, Blood

Test Down Notes

LRBA is temporarily test down due to reagent issues.


Ordering Guidance


This flow cytometry test is complementary to genetic testing.



Shipping Instructions


Testing is performed Monday through Friday. Specimens not received by 4 p.m. (CST) on Friday may be cancelled.

 

Collect and package specimen as close to shipping time as possible. It is recommended that specimens arrive within 24 hours of collection.

 

Samples arriving on the weekend and observed holidays may be canceled.



Necessary Information


Ordering healthcare professional name and phone number are required.



Specimen Required


Container/Tube: Lavender top (EDTA)

Specimen Volume: 3 mL

Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.


Secondary ID

608113

Useful For

Aiding in the diagnosis of lipopolysaccharide-responsive beige-like anchor protein (LRBA) deficiency

 

This test is not useful for identifying a carrier status for LRBA deficiency.

Highlights

The test determines the percentage and intensity of expression of lipopolysaccharide-responsive beige-like anchor (LRBA) protein on T cells and B cells in peripheral blood.

 

It can be used as a screening step prior to genetic testing for LRBA; to confirm the finding of an established disease-causing alteration in LRBA at the protein level; and to examine the effect of reported genetic variants of undetermined significance on LRBA protein expression.

 

It can help distinguish LRBA deficiency from conditions with overlapping clinical manifestations, including immune dysregulation and autoimmunity, such as immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX)-like syndromes; early onset hypogammaglobulinemia; common variable immune deficiency; inflammatory bowel disease; and autoimmune lymphoproliferative syndrome.

Method Name

Flow Cytometry

Reporting Name

LRBA Deficiency, B

Specimen Type

Whole Blood EDTA

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood EDTA Ambient 48 hours PURPLE OR PINK TOP/EDTA

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus OK

Clinical Information

Lipopolysaccharide-responsive beige-like anchor protein (LRBA) deficiency is a rare autosomal recessive primary immunodeficiency disease (also known as inborn errors of immunity) caused by homozygous or compound heterozygous loss-of-function variants in the LRBA gene. It has a wide spectrum of clinical manifestations, including immune dysregulation and autoimmunity, inflammatory bowel disease, early-onset hypogammaglobulinemia, recurrent infections and organomegaly.

Reference Values

The appropriate reference values will be provided on the report.

Interpretation

The results are reported as the percentage and MFI (mean fluorescence intensity) of lipopolysaccharide-responsive beige-like anchor protein (LRBA) expression in T cells and B cells.

 

The majority of genetically confirmed cases of LRBA deficiency lead to the absence of LRBA expression. Therefore, the lack of LRBA expression in T and B cells is consistent with LRBA deficiency. In this case, genetic analysis of LRBA to confirm the diagnosis and to identify the underlying variant will be recommended.

 

In addition, there are reported cases of LRBA deficiency where the protein is expressed but at lower intensity. Therefore, the expression of LRBA at diminished intensity could be due to a disease-causing LRBA variant, which would have to be confirmed or ruled out by genetic and functional analysis.

Method Description

The lipopolysaccharide-responsive beige-like anchor (LRBA) protein expression assay is performed on EDTA whole blood. Samples are fixed, permeabilized and stained with antibodies specific for CD45, CD14, CD19, CD3, and CD56 along with either the LRBA antibody (unconjugated) or isotype control (unconjugated). A secondary reporter antibody is added to allow the assessment of LRBA and isotype control expression. Samples are then analyzed on a flow cytometer. LRBA expression is evaluated on the following populations: T-cells: (CD45+CD14negCD3+) and B-cells: (CD45+CD14negCD3negCD19+).(Unpublished Mayo method)

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed using an analyte specific reagent. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

86356 x 2

LOINC Code Information

Test ID Test Order Name Order LOINC Value
LRBA LRBA Deficiency, B In Process

 

Result ID Test Result Name Result LOINC Value
608960 %CD3+LRBA+ In Process
608964 MFI CD3+LRBA+ In Process
608961 %CD19+LRBA+ In Process
608965 MFI CD19+LRBA+ In Process
608968 LRBA Interpretation 69052-9

Day(s) Performed

Monday through Friday