X-Linked Hyper IgM Syndrome, Blood
Use
This test is designed for screening X-linked hyper-IgM (XL-HIGM) syndrome or CD40L deficiency, primarily in male patients younger than 10 years. It aids in the identification of XL-HIGM carrier status in women of child-bearing age (younger than 45 years). XL-HIGM is a severe primary immunodeficiency characterized by defective T-cell function, particularly affecting the CD40L gene, which is crucial for B-cell interaction, class switch recombination, and germinal center formation. Patients with XL-HIGM are particularly susceptible to opportunistic infections due to compromised immunological responses.
Special Instructions
Testing is not performed on Saturdays, Sundays, or observed holidays. Specimens should not be shipped for arrival on days when testing is not performed. Specimen collection should be timed as closely to shipping as possible, ideally within 24 hours of collection. This ensures specimen viability for testing, particularly for the CD40L expression and function assessment via flow cytometry.
Limitations
This test is not typically indicated for male patients older than 10 years or women beyond child-bearing age (>45 years). Incorrect specimen handling can lead to variable T-cell activation, especially in samples tested between 48-72 hours after collection. In cases where normal CD40L expression and binding are present but the clinical phenotype suggests hyper-IgM syndrome, alternative genetic mutations might need to be evaluated. This includes potential considerations for genetic variants in CD40, AICDA, and UNG which are also associated with hyper-IgM syndrome forms.
Methodology
Cell-based / Cytometry (Flow Cytometry)
Biomarkers
LOINC Codes
- 98239-7
- 98241-3
- 98240-5
- 69052-9
Result Turnaround Time
3-4 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
4 mL
Minimum Volume
1.2 mL
Container
Green top (sodium heparin)
Collection Instructions
Send whole blood specimen in the original tube. Do not aliquot.
Storage Instructions
It is recommended that specimens arrive within 24 hours of collection. Specimens must be kept at ambient temperature and should not be collected or shipped on weekends or holidays.
Causes for Rejection
Gross hemolysis or gross lipemia will result in rejection of the specimen.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 72 hours |