Schnyder Crystalline Corneal Dystrophy (SCCD) via the UBIAD1 Gene
Summary and Pricing 
Test Method
Exome Sequencing with CNV Detection
| Test Code | Test Copy Genes | Test CPT Code | Gene CPT Codes Copy CPT Code | Base Price | |
|---|---|---|---|---|---|
| 8925 | UBIAD1 | 81479 | 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. If the Sanger option is selected, CNV detection may be ordered through Test #600.
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.
Clinical Features and Genetics
Clinical Features
Schnyder crystalline corneal dystrophy (SCCD) is an autosomal dominant disorder with high penetrance. Clinically, SCCD is characterized by abnormal corneal lipid metabolism, progressive bilateral corneal opacification, which may result in glare and disproportionate loss of photopic vision with well-preserved scotopic vision into the 5th decade and beyond (McCarthy et al. 1994; Weiss 2007; Weiss and Khemichian 2011; Nickerson et al. 2013).
Genetics
Autosomal dominant SCCD is caused by mutations in the UBIAD1 gene located on chromosome 1p36. UBIAD1 (UbiA prenyltransferase domain containing 1) encodes a membrane protein containing a prenyltransferase domain, which is similar to the E. coli protein, UbiA. UBIAD1 protein, which is shown to be localized sub-cellularly to mitochondria, is involved in cholesterol synthesis and storage. Recently, UBIAD1 was also shown to be involved in the synthesis of menaquinone-4 (MK-4, vitamin K(2)), which is essential for the maintenance of cornea health and visual acuity (Nickerson et al. 2010; Nickerson et al. 2013). So far, about 25 missense mutations in UBIAD1 that are associated with SCCD have been reported (Human Gene Mutation Database). The mutation c.305A>G (Asn102Ser) is reported to be a founder mutation in the Polish population (Nowinska et al. 2014).
Clinical Sensitivity - Sequencing with CNV PGxome
A mutation screening in six unrelated pedigrees clinically diagnosed with SCCD identified UBIAD1 mutations in all of the families. A potential mutation hot spot was observed at amino acid Asn102 in five out of six families. The observed mutations were not found in 200 control chromosomes (Weiss et al. 2007).
Testing Strategy
This test provides full coverage of all coding exons of the UBIAD1 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
All patients with symptoms suggestive of corneal dystrophy with abnormal lipid deposition in cornea are candidates.
All patients with symptoms suggestive of corneal dystrophy with abnormal lipid deposition in cornea are candidates.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| UBIAD1 | 611632 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Disease
| Name | Inheritance | OMIM ID |
|---|---|---|
| Schnyder Crystalline Corneal Dystrophy | AD | 121800 |
Citations
- Human Gene Mutation Database (Bio-base).
- McCarthy M, Innis S, Dubord P, White V. 1994. Panstromal Schnyder corneal dystrophy. A clinical pathologic report with quantitative analysis of corneal lipid composition. Ophthalmology 101: 895–901. PubMed ID: 8190477
- Nickerson ML, Bosley AD, Weiss JS, Kostiha BN, Hirota Y, Brandt W, Esposito D, Kinoshita S, Wessjohann L, Morham SG, Andresson T, Kruth HS, Okano T, Dean M. 2013. The UBIAD1 prenyltransferase links menaquinone-4 [corrected] synthesis to cholesterol metabolic enzymes. Hum. Mutat. 34: 317–329. PubMed ID: 23169578
- Nickerson ML, Kostiha BN, Brandt W, Fredericks W, Xu K-P, Yu F-S, Gold B, Chodosh J, Goldberg M, Lu DW, Yamada M, Tervo TM, Grutzmacher R, Croasdale C, Hoeltzenbein M, Sutphin J, Malkowicz SB, Wessjohann L, Kruth HS, Dean M, Weiss JS. 2010. UBIAD1 Mutation Alters a Mitochondrial Prenyltransferase to Cause Schnyder Corneal Dystrophy. PLoS ONE 5: e10760. PubMed ID: 20505825
- Nowinska AK, Wylegala E, Teper S, Lyssek-Boron A, Aragona P, Roszkowska AM, Micali A, Pisani A, Puzzolo D. 2014. Phenotype-genotype correlation in patients with Schnyder corneal dystrophy. Cornea 33: 497–503. PubMed ID: 24608252
- Weiss JS, Khemichian AJ. 2011. Differential diagnosis of Schnyder corneal dystrophy. Dev Ophthalmol 48: 67–96. PubMed ID: 21540632
- Weiss JS, Kruth HS, Kuivaniemi H, Tromp G, White PS, Winters RS, Lisch W, Henn W, Denninger E, Krause M, Wasson P, Ebenezer N, Mahurkar S, Nickerson ML. 2007. Mutations in the UBIAD1 Gene on Chromosome Short Arm 1, Region 36, Cause Schnyder Crystalline Corneal Dystrophy. Investigative Ophthalmology & Visual Science 48: 5007–5012. PubMed ID: 17962451
Ordering/Specimens
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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ORDER OPTIONS
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2) Select Additional Test Options
No Additional Test Options are available for this test.