Carbohydrate Deficient Transferrin for Congenital Glycosylation Disorders (Sendout)

General Information

Lab Name

Lab Code

514

External Test Id

CDG

Description

Useful For:

Screening for congenital disorders of glycosylation

Test Information: Carbohydrate-deficient transferrin is a marker for the autosomal recessive disorder previously known as carbohydrate deficient glycoprotein syndrome (CDGS). CDGS is caused by various defects involving the glycosylation of glycoproteins. Depending on the site of the biochemical defect and the clinical presentation, 5 different forms of this syndrome have been described to date. These disorders were recently combined in a larger group of diseases termed "congenital disorders of glycosylation" (CDG).

This testing is used to screen patients for suspected congenital disorders of glycosylation (N- and O-glycosylation defects as well as glycan structure analysis). Congenital disorders of glycosylation (CDG) encompass over 150 genetic conditions spanning a broad clinical spectrum. The main CDG profiles that can be identified by this analysis are type I, some type II, and mixed type CDG.

Ordering Requirements: Include the reason for testing (developmental delay, congenital disorders of glycosylation, follow-up of known patient with CDG) in the Epic Order Comment. This test is not intended for evaluation of alcohol abuse.

Synonyms

CDG, CDGN, CDT, Transferrin ISO, Transferrin isoelectric focusing

Components

Interpretation

Method

Affinity Chromatography-Mass Spectrometry (MS)

Reference Range

Ref. Range Notes

Reference Values:

Ratio	Normal	Indeterminate	Abnormal
Transferrin mono-oligo/di-oligo ratio:	< or =0.06	0.07-0.09	> or =0.10
Transferrin A-oligo/di-oligo ratio:	< or =0.011	0.012-0.021	> or =0.022
Transferrin tri-sialo/di-oligo ratio:	< or =0.05	0.06-0.12	> or =0.13
Apo CIII-1/Apo CIII-2 ratio:	< or =2.91	2.92-3.68	> or =3.69
Apo CIII-0/Apo CIII-2 ratio:	< or =0.48	0.49-0.68	> or =0.69

Interferences and Limitations

Cautions:

Other conditions such as acute crisis of hereditary fructose intolerance, galactosemia, substance abuse, and acute liver disease may have a congenital disorders of glycosylation (CDG) profile that is indistinguishable from any other true CDG type I cases. Relevant clinical information and the indication for the analysis should be provided with the specimen.

Transferrin glycosylation patterns may normalize so repeat testing is warranted in patients with significant clinical suspicion.

Ordering & Collection

Specimen Type

Blood

Collection

3 mL blood in GOLD SST or RED TOP tube

Handling Instructions

Outside Laboratories:

Centrifuge sample and transfer serum to a separate plastic vial, leaving room at the top for expansion. Freeze serum at -20°C while awaiting shipment. Transport on dry ice.
The reason for testing (developmentally delay, congenital disorders of glycosylation, follow-up of known patient with CDG, etc.) is required. Include this information on the DLMP requisition.

Stability: Frozen (preferred): 45 days; Refrigerated: 28 days; Ambient: 7 days.

Quantity

Requested: 1 mL serum
Minimum: 0.5 mL serum

Processing

Receiving Instructions

Centrifuge sample and transfer serum to a separate plastic vial, leaving room at the top for expansion. Freeze serum at -20°C.

Login: SEND1-;FREEZE

RSNDT1: MAYO
RSTYP1: SRM
RTSRQ1: ;Carbohydrate Deficient Transferrin (Mayo Test CDG)

Sendouts:

Order Mayo Test: CDG.
Indicate the "Reason for Referral" in the MayoAccess order.
Note: For adult patients (>21 yrs), confirm the reason for testing. If provider indicates testing for evaluation of alcohol abuse, contact the Laboratory Medicine Resident for review.

Stability: Frozen (preferred): 45 days; Refrigerated: 28 days; Ambient: 7 days.

Misc Sendout

Performance

Lab Department

Frequency

Performed: Monday, Thursday. Reported: 3-6 days from sample receipt at Mayo.

Available STAT?

Performing Location(s)

Sendout	Mayo Clinic Laboratories 800-533-1710 200 First Street Southwest Rochester, MN 55901

Billing & Coding

Billing Comments: CPT: 82373