Test Overview
Test Methodology

Relative-quantitative PCR uses TaqMan probe and primers to amplify and detect a targeted DNA segment so that the copy number of the target can be calculated in comparison to a calibrator DNA sample. The relative copy number of the target region is calculated based on a calibrator copy number of "two" for most genomic regions.
The Illumina CytoSNP-850K Chromosomal Microarray (CMA) may not detect low-level mosaicism, and cannot detect chromosomal aberrations that do not result in net gains or losses of genomic material, such as balanced chromosomal rearrangements (balanced translocations, balanced insertions, and inversions), rearrangements in repeat sequences (short arms of acrocentric chromosomes and heterochromatic regions), point mutations, indels, and epigenetic alterations. CMA will not detect genomic imbalances in regions that are not represented on the array.

Test Usage

Confirmation of a clinical or a suspected diagnosis of DiGeorge syndrome in a patient. Tier 1 of this panel includes rqPCR using multiple TaqMan probes within the most common region deleted in the 22q11.2 deletion. This panel test will automatically reflex to Tier 2 (Chromosomal Microarray, CMA) when rqPCR detects a normal genomic copy number or if only one the TaqMan probes detects an abnormal genomic copy within the 22q11.2 region. However, if multiple TaqMan probes detect an abnormal copy number, then a reflexive CMA will not be performed. In this case, a physician can order an add-on CMA test if desired.

Reference Range *

Interpretive report provided.

Test Details
Days Set Up
Monday - Friday
Analytic Time

Tier 1 (DIGP1)(rqPCR): 7 days; Tier 2 (DIGP2)(microarray): 28 days.

Soft Order Code
DIGP1
MiChart Code
DiGeorge Panel: Reflex to all Tiers
Synonyms
  • Chromosomal Microarray (CMA)
  • DIGP2
  • Velocardiofacial Syndrome (VCFS)
  • CATCH 22
  • SNPM1
  • DIGP1
  • rqPCR for 22q11.2 deletion
Laboratory
MMGL
Section
MMGL Molecular Genetics
Specimen Requirements
Collection Instructions

Collect specimen in a lavender top tube. Send intact specimen within 24 hours if stored at room temperature or within 5 days if stored refrigerated. Include the patient's family history, pedigree, and ethnicity on the test requisition. Obtaining informed consent from the patient prior to genetic testing is strongly recommended. If desired, a UMHS Request and Consent for Genetic Testing form can be obtained from the MMGL Molecular Genetics Laboratory by contacting the MLabs Client Services Center at 800-862-7284 or online at https://mlabs.umich.edu/sites/default/files/2020-01/file/pci-mmgl_infor….

Lavender Top Tube
Normal Volume
5 - 10 mL EDTA whole blood
Minimum Volume
2 mL EDTA whole blood
Additional Information

The DiGeorge Panel (order code DIGP1) includes rqPCR (Tier 1), and if rqPCR detects a normal genomic copy number or only one the TaqMan probes detects an abnormal genomic copy within the 22q11.2 region then Chromosomal Microarray (CMA) (order code DIGP2) is performed (Tier 2). By ordering this test the clinician acknowledges that additional reflex testing will be performed and billed at a separate additional charge if indicated. By ordering this test the clinician acknowledges that informed consent has been obtained from the patient as required by applicable state or federal laws and the ordering clinician has authorization from the patient permitting MLabs to report the test results to the ordering clinician. Test includes medical geneticist interpretation of results billed as a separate additional charge. This test is not available without interpretation.

Billing
CPT Code
81402
Fee Code
DA082
Pro Fee CPT
G0452-26
Reflex CPT
81229
Reflex Fee Code
DA083
NY State Approved
No