CDT Congenital Glycosylation

Label Mnemonic:	CDG
Epic code:	LAB7371
Downtime form:	A-1a Doctor/Provider Orders - Pathology Core and Specialty Care Nursery

Commercial Mailout Laboratory
6240-8 RCP
356-8593

Specimen(s):

Serum

Specimen Instructions:

Please provide a reason for referral with each specimen.

Draw blood in a plain, red-top tube.

Note: This test is for congenital disorders of glycosylation.

Patient's age is required on request form for processing.

Collection Medium:

Red top tube 5 mL (Clot Activator)

Minimum:

0.1 mL of serum

Delivery Instructions:

Submit specimen to laboratory as soon as possible after collection.

Turn Around Time:

5 days upon receipt at reference laboratory

Reference Range:

Ratio                                 Normal   Indeterminate   Abnormal
Transferrin Mono-oligo/Di-          < or =0.06   0.07-0.09   > or =0.10
   oligo Ratio
Transferrin A-oligo/Di-             < or =0.011  0.012-0.021 > or =0.022
   oligo Ratio
Transferrin Tri-sialo/Di-           < or =0.05   0.06-0.12   > or =0.13
   oligo Ratio
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

Interpretive Data:

Positive test results could be due to a genetic or nongenetic 
condition; additional confirmatory testing is required.

Results are reported as the mono-oligosaccharide/di-oligosaccharide 
transferrin ratio, the a-oligosaccharide/di-oligosaccharide transferrin 
ratio, the tri-sialo/di-oligosaccharide transferrin ratio, and the 
apolipoprotein CIII-1/apolipoprotein CIII-2 ratio, and the 
apolipoprotein CIII-0/apolipoprotein CIII-2 ratio. The report will 
include the quantitative results and an interpretation.

The congenital disorders of glycosylation (CDG) profiles are 
categorized in 4 types. 

When the profile cannot be categorized following the above 
classification, all the abnormal transferrin and/or Apo-CIII species 
will be reported descriptively according to the molecular mass stating 
the possible structures.

Comments:

Congenital disorders of glycosylation (CDG), formerly known as carbohydrate-deficient glycoprotein syndrome, are a group of more than 45 inherited metabolic disorders affecting several steps of the pathway involved in the glycosylation of proteins. CDG are classified into 2 groups. Type I CDG is characterized by defects in the assembly or transfer of the dolichol-linked glycan, while type II involves processing defects of the glycan. Apolipoprotein CIII (Apo-CIII) isoforms, a protein with a single core 1 mucin type O-glycosylate protein, is a complementary evaluation for the CDG type II profile. This analysis will evaluate mucin type O-glycosylation, a defect that happens in the Golgi apparatus, and will change the ratios, increasing the asialo or monoisalo forms and decreasing the fully sialilate (disialo) forms. In young children (>1 month) and in liver disease, the Apo-CIII2 may be increased. Children younger than 6 months, and clinically suspected of having ATP6V0A2-CDG, may have normal transferrin profile with abnormal Apo-CIII profile.

Useful For
Screening for congenital disorders of glycosylation.

Methodology:

Affinity Chromatography/Mass Spectrometry (MS)

CPT Code:

82373

See also:
Carbohydrate Deficient Transferrin, Serum