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Test Code XHIM X-Linked Hyper IgM Syndrome, Blood

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Screening for X-linked hyper-IgM (XL-HIGM) or CD40L deficiency, primarily in male patients younger than 10 years of age

 

Ascertaining XL-HIGM carrier status in females of child-bearing age younger than 45 years of age

Method Name

Flow Cytometry

Reporting Name

X-Linked Hyper IgM Syndrome, B

Specimen Type

WB Sodium Heparin


Shipping Instructions


Specimens are required to be received in the laboratory weekdays and by 4 p.m. on Friday. Draw and package specimen as close to shipping time as possible.

 

It is recommended that specimens arrive within 24 hours of draw.

 

Samples arriving on the weekend may be canceled.



Necessary Information


Ordering physician's name and phone number are required.



Specimen Required


For serial monitoring, we recommend that specimen draws be performed at the same time of day.

 

Container/Tube: Green top (sodium heparin)

Specimen Volume: 4 mL

Collection Instructions: 

1. Send specimen in original tube. Do not aliquot.

2. Specimens received more than 72 hours after collection will be rejected and the assay will not be performed.


Specimen Minimum Volume

1.2 mL

Specimen Stability Information

Specimen Type Temperature Time
WB Sodium Heparin Ambient 72 hours

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross reject

Icterus

NA

Other

Lithium heparin; Green top microtube (lithium heparin)

Reference Values

Present

Interpretation

This is a qualitative assay; CD40L-protein expression and function is reported as present or absent. Absence of CD40L-protein expression and function is consistent with X-linked hyper-IgM (XL-HIGM). In females, the presence of 2 populations-normal and abnormal-is consistent with carrier status.

 

Most patients (80%-90%) with XL-HIGM have absent or significantly reduced CD40L expression on their activated CD4 T cells. Patients with normal CD40L expression, but abnormal function, show an absence of binding with soluble chimeric CD40-uIg antibody, substantiating a diagnosis of XL-HIGM. Females who are carriers for this disease will show a typical bimodal pattern of CD40L expression, with 50% of the T cells lacking any CD40L expression. In the case of aberrant protein function, a similar profile will be obtained with the CD40-uIg antibody.

 

CD69 is a marker for T-cell activation and serves as a positive control; in the absence of induced CD69 expression on T cells, the presence of XL-HIGM cannot be assessed.

Day(s) and Time(s) Performed

Monday through Friday

Specimens are required to be received in the laboratory on weekdays and by 4 p.m. on Friday. No weekend processing

Analytic Time

3 days

Specimen Retention Time

4 days

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 U.S. Food and Drug Administration.

CPT Code Information

88184-Flow cytometry, cell surface, cytoplasmic

88185 x 6-Each additional marker

LOINC Code Information

Test ID Test Order Name Order LOINC Value
XHIM X-Linked Hyper IgM Syndrome, B In Process

 

Result ID Test Result Name Result LOINC Value
82964 CD40 Ligand Expression In Process
29040 CD40muIg (Function) In Process
23901 Interpretation 69052-9