Test Id : CDGN
Congenital Disorders of N-Glycosylation, Serum
Useful For
Suggests clinical disorders or settings where the test may be helpful
Screening for N-linked congenital disorders of glycosylation
Providing information on specific structural oligosaccharide abnormalities to potentially direct further genetic testing
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
Congenital disorders of glycosylation (CDG) comprise a large group of inborn errors of metabolism affecting predominantly N- and O-glycosylation of proteins.
N-linked CDG commonly present as clinical syndromes with multisystemic involvement and a broad clinical spectrum.
In addition to transferrin and apolipoprotein CIII isoform analysis, this test also detects and analyzes serum N-linked oligosaccharides by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for a more comprehensive evaluation of CDG.
Additional Tests
Lists tests that are always performed, at an additional charge, with the initial tests.
| Test Id | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| CDG | CDG, S | Yes | Yes |
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
When this test is ordered, carbohydrate deficient transferrin for congenital disorders will always be performed at an additional charge.
For more information see Congenital Disorders of Glycosylation: Screening Algorithm.
Method Name
A short description of the method used to perform the test
Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS)
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Aliases
Lists additional common names for a test, as an aid in searching
Carbohydrate Deficient Glycoprotein Syndrome (CDGS)
CDG (Congenital Disorders of Glycosylation)
N-linked Glycosylation Disorders
N-glycan
N-linked glycosylation
N-linked oligosaccharides
N glycosylation
Glycoprotein
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
When this test is ordered, carbohydrate deficient transferrin for congenital disorders will always be performed at an additional charge.
For more information see Congenital Disorders of Glycosylation: Screening Algorithm.
Specimen Type
Describes the specimen type validated for testing
Serum
Ordering Guidance
This test is for congenital disorders of glycosylation. For evaluation of alcohol abuse, order CDTA / Carbohydrate Deficient Transferrin, Adult, Serum.
Necessary Information
1. Patient’s age is required.
2. Reason for testing is required.
ORDER QUESTIONS AND ANSWERS
| Question ID | Description | Answers |
|---|---|---|
| BG712 | Reason for Referral |
Developmentally delayed Congenital disorders of glycosylation Follow-up of known patient with CDG Evaluation of alcohol abuse - change test to 82425 (CDTA) Carb Def Transferrin, Adult, S |
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 0.15 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Special Instructions
Library of PDFs including pertinent information and forms related to the test
Forms
1. Congenital Disorders of Glycosylation Patient Information
2. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
0.1 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| Gross hemolysis | Reject |
| Gross lipemia | OK |
| Gross icterus | OK |
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 28 days | |
| Ambient | 7 days | ||
| Frozen | 45 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Screening for N-linked congenital disorders of glycosylation
Providing information on specific structural oligosaccharide abnormalities to potentially direct further genetic testing
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
Congenital disorders of glycosylation (CDG) comprise a large group of inborn errors of metabolism affecting predominantly N- and O-glycosylation of proteins.
N-linked CDG commonly present as clinical syndromes with multisystemic involvement and a broad clinical spectrum.
In addition to transferrin and apolipoprotein CIII isoform analysis, this test also detects and analyzes serum N-linked oligosaccharides by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for a more comprehensive evaluation of CDG.
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
When this test is ordered, carbohydrate deficient transferrin for congenital disorders will always be performed at an additional charge.
For more information see Congenital Disorders of Glycosylation: Screening Algorithm.
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Congenital disorders of glycosylation (CDG) are a group of over 150 inherited metabolic disorders largely affecting N- and O-glycosylation of proteins. The majority of CDG are attributed to congenital defects in N-glycosylation, which take place primarily in the cytoplasm and in the membranes of the endoplasmic reticulum. O-glycosylation defects are frequently tissue specific and present differently than classic N-linked defects. CDG are currently classified into 2 main groups. Type I CDG is characterized by defects in the assembly or transfer of the dolichol-linked glycan (sugar chain), while type II involves processing defects of the glycan. Depending on the specific defect, an N-glycosylation disorder can be either a type I or type II CDG.
N-linked CDG are phenotypically diverse, usually presenting as clinical syndromes with multisystemic involvement and a broad clinical spectrum. There is considerable variation in the severity of this group of diseases ranging from a mild presentation in adults to severe multi-organ dysfunction causing infantile lethality. Intellectual disability is common, although in some subtypes, phosphomannose isomerase-CDG (MPI-CDG or CDG type Ib) in particular, intellect is preserved. CDG should be considered in all patients with multisystem disease and in those with neurologic abnormalities, including developmental delay and seizures; brain abnormalities, such as cerebellar atrophy or hypoplasia; and unexplained liver dysfunction. Additional common symptoms that may be present include abnormal subcutaneous fat distribution; gastrointestinal issues, such as vomiting, chronic diarrhea, and protein-losing enteropathy; eye abnormalities, including retinal degeneration and strabismus; and cardiomyopathy.
Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry analysis of released N-linked oligosaccharides, as performed in this assay, is a global assessment of N-linked glycosylation. This complements the also performed transferrin and apolipoprotein CIII isoform analysis (see CDG / Carbohydrate Deficient Transferrin for Congenital Disorders of Glycosylation, Serum) by providing additional information on specific structural oligosaccharide abnormalities that can guide molecular testing.
Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
An interpretive report will be provided.
Interpretation
Provides information to assist in interpretation of the test results
The results of the transferrin and apolipoprotein CIII isoform analysis are followed up with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry analysis of released N-linked oligosaccharides to assess N-linked glycosylation. Reports of abnormal results will include recommendations for additional biochemical and molecular genetic studies to identify more precisely the specific congenital disorder of glycosylation. If applicable, treatment options, the name and telephone number of contacts who may provide studies, and a telephone number for one of the laboratory directors (if the referring physician has additional questions) will be provided.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
No significant cautionary statements
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Sparks SE, Krasnewich DM. Congenital disorders of N-linked glycosylation and multiple pathway overview. In: Adam MP, Ardinger HH, Pagon RA, et al, eds. GeneReviews [Internet]. University of Washington, Seattle; 2005. Updated January 12, 2017. Accessed March 1, 2024. Available at www.ncbi.nlm.nih.gov/books/NBK1332/
2. Chang IJ, He M, Lam CT. Congenital disorders of glycosylation. Ann Transl Med. 2018;6(24):477. doi:10.21037/atm.2018.10.45
3. Francisco R, Marques-da-Silva D, Brasil S, et al. The challenge of CDG diagnosis. Mol Genet Metab. 2019;126(1):1-5. doi:10.1016/j.ymgme.2018.11.003
4. Freeze HH, Chong JX, Bamshad MJ, Ng BG. Solving glycosylation disorders: fundamental approaches reveal complicated pathways. Am J Hum Genet. 2014;94(2):161-175. doi:10.1016/j.ajhg.2013.10.024
5. Verheijen J, Tahata S, Kozicz T, et al. Therapeutic approaches in congenital disorders of glycosylation (CDG) involving N-linked glycosylation: an update. Genet Med. 2020;22(2):268-279. doi:10.1038/s41436-019-0647-2
6. Francisco R, Brasil S, Poejo J, et al. Congenital disorders of glycosylation (CDG): state of the art in 2022. Orphanet J Rare Dis. 2023;18(1):329. doi:10.1186/s13023-023-02879-z
Method Description
Describes how the test is performed and provides a method-specific reference
N-linked oligosaccharides are enzymatically released, purified, and then detected by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry.(Unpublished Mayo method)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Wednesday
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location
Indicates the location of the laboratory that performs the test
Fees :
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Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
83789
LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| CDGN | CDGN, S | 90417-7 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| 602577 | Interpretation | 59462-2 |
| BG712 | Reason for Referral | 42349-1 |
| 602576 | Reviewed By | 18771-6 |