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Congenital Disorders of Glycosylation, Type IIj via the COG4 Gene

Summary and Pricing

Test Method

Exome Sequencing with CNV Detection
Test Code Test Copy GenesTest CPT Code Gene CPT Codes Copy CPT Codes Base Price
COG4 81479 81479,81479 $990
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
8069COG481479 81479,81479 $990 Order Options and Pricing

Pricing Comments

Our favored testing approach is exome based NextGen sequencing with CNV analysis. This will allow cost effective reflexing to PGxome or other exome based tests. However, if full gene Sanger sequencing is desired for STAT turnaround time, insurance, or other reasons, please see link below for Test Code, pricing, and turnaround time information.

An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.

Click here for costs to reflex to whole PGxome (if original test is on PGxome Sequencing platform).

Click here for costs to reflex to whole PGnome (if original test is on PGnome Sequencing platform).

The Sanger Sequencing method for this test is NY State approved.

For Sanger Sequencing click here.

Turnaround Time

3 weeks on average for standard orders or 2 weeks on average for STAT orders.

Please note: Once the testing process begins, an Estimated Report Date (ERD) range will be displayed in the portal. This is the most accurate prediction of when your report will be complete and may differ from the average TAT published on our website. About 85% of our tests will be reported within or before the ERD range. We will notify you of significant delays or holds which will impact the ERD. Learn more about turnaround times here.

Targeted Testing

For ordering sequencing of targeted known variants, go to our Targeted Variants page.


Genetic Counselors


  • Hongjie Chen

Clinical Features and Genetics

Clinical Features

Congenital disorders of glycosylation (CDGs) are a group of heterogeneous disorders due to a defect in the linkage of oligosaccharides to proteins. This process involves covalent attachment of carbohydrate chains to the amide group of asparagine (N-glycoprotein) or less commonly to the hydroxyl group of serine/threonine (O-glycoprotein). Congenital disorders of glycosylation result in a wide variety of clinical features due to multisystem involvement, and include defects in nervous system development, psychomotor retardation, dysmorphic features, hypotonia, coagulation disorders, and immunodeficiency (Sparks and Krasnewich 2014; Scott et al. 2014) .

Thus far, only two patients with CDG IIj (COG-CDG) have been described. Onset occurs before one year of age with failure to thrive in infancy. The first patient with CDG IIj presented at 4 months of age with fever, irritability, and complex seizures after vaccination (Reynders et al. 2009). He also exhibited axial hypotonia, peripheral hypotonia, and hyperreflexia along with mild dysmorphic features such as down-sloping frontal area and thick hair. This patient also developed recurrent respiratory infections. By 3 years of age he had microcephaly, cerebral atrophy, ataxia, absence of speech, and psychomotor retardation. A second patient presented at 11 months of age with failure to thrive, recurrent diarrhea, and recurrent respiratory and gastrointestinal infections with sepsis (Ng et al. 2011). Other features included developmental delay, hypotonia, nystagmus, hepatosplenomegaly, and poor growth. Seizures developed at 16 months and an infection was ultimately fatal around 2 years of age. Both patients showed deficiencies in sialylation and galactosylation.


All CDGs exhibit autosomal recessive inheritance. More than 40 genes have been found to be involved with CDGs, but the majority of these have only been reported in a small number of individual patients (Sparks and Krasnewich 2014). The COG4 gene encodes a subunit of the conserved oligomeric Golgi (COG) complex which is composed of eight subunits. It functions as a vesicular tether during retrograde Golgi trafficking which is important for the recycling of Golgi resident proteins (such as glycosylation enzymes) that are essential for the proper glycosylation of secretory proteins (Willett et al. 2013). Defects in COG subunits that lead to aberrant glycosylation are likely a result of abnormal transport or distribution of glycosylation enzymes. Patients with COG4 pathogenic variants are considered to present with a milder phenotype in comparison to the other COG gene deficiencies (Reynders et al. 2009). Missense variants, a nonsense variant, and a small deletion are thus far the only pathogenic variants reported.

Clinical Sensitivity - Sequencing with CNV PGxome

Clinical sensitivity cannot be estimated because only a small number of patients have been reported. Analytical sensitivity should be high because all reported causative mutations thus far are detectable by sequencing.

Testing Strategy

This test provides full coverage of all coding exons of the COG4 gene plus 10 bases of flanking noncoding DNA in all available transcripts along with other non-coding regions in which pathogenic variants have been identified at PreventionGenetics or reported elsewhere. We define full coverage as >20X NGS reads or Sanger sequencing. PGnome panels typically provide slightly increased coverage over the PGxome equivalent. PGnome sequencing panels have the added benefit of additional analysis and reporting of deep intronic regions (where applicable).

Dependent on the sequencing backbone selected for this testing, discounted reflex testing to any other similar backbone-based test is available (i.e., PGxome panel to whole PGxome; PGnome panel to whole PGnome).

Indications for Test

Candidates for this test are patients with biochemical findings and/or clinical symptoms consistent with CDG IIj; specifically, a transferrin isoform analysis suggestive of CDG type II. Testing is also indicated for family members of patients who have known COG4 pathogenic variants. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in COG4.


Official Gene Symbol OMIM ID
COG4 606976
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT


Name Inheritance OMIM ID
Congenital Disorder Of Glycosylation Type IIj AR 613489


  • Ng BG, Sharma V, Sun L, Loh E, Hong W, Tay SKH, Freeze HH. 2011. Identification of the first COG-CDG patient of Indian origin. Mol. Genet. Metab. 102: 364–367. PubMed ID: 21185756
  • Reynders E, Foulquier F, Leão Teles E, Quelhas D, Morelle W, Rabouille C, Annaert W, Matthijs G. 2009. Golgi function and dysfunction in the first COG4-deficient CDG type II patient. Hum. Mol. Genet. 18: 3244–3256. PubMed ID: 19494034
  • Scott K, Gadomski T, Kozicz T, Morava E. 2014. Congenital disorders of glycosylation: new defects and still counting. J. Inherit. Metab. Dis. 37: 609-617. PubMed ID: 24831587
  • Sparks SE, Krasnewich DM. 2014. Congenital Disorders of N-linked Glycosylation Pathway Overview. In: Pagon RA, Adam MP, Ardinger HH, Bird TD, Dolan CR, Fong C-T, Smith RJ, and Stephens K, editors. GeneReviews(®), Seattle (WA): University of Washington, Seattle. PubMed ID: 20301507
  • Willett R, Ungar D, Lupashin V. 2013. The Golgi puppet master: COG complex at center stage of membrane trafficking interactions. Histochemistry and Cell Biology 140: 271–283. PubMed ID: 23839779


Ordering Options

We offer several options when ordering sequencing tests. For more information on these options, see our Ordering Instructions page. To view available options, click on the Order Options button within the test description.

myPrevent - Online Ordering

  • The test can be added to your online orders in the Summary and Pricing section.
  • Once the test has been added log in to myPrevent to fill out an online requisition form.
  • PGnome sequencing panels can be ordered via the myPrevent portal only at this time.

Requisition Form

  • A completed requisition form must accompany all specimens.
  • Billing information along with specimen and shipping instructions are within the requisition form.
  • All testing must be ordered by a qualified healthcare provider.

For Requisition Forms, visit our Forms page

If ordering a Duo or Trio test, the proband and all comparator samples are required to initiate testing. If we do not receive all required samples for the test ordered within 21 days, we will convert the order to the most effective testing strategy with the samples available. Prior authorization and/or billing in place may be impacted by a change in test code.

Specimen Types

Specimen Requirements and Shipping Details

PGxome (Exome) Sequencing Panel

PGnome (Genome) Sequencing Panel

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Note: acceptable specimen types are whole blood and DNA from whole blood only.
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