Choroideremia via the CHM Gene
Summary and Pricing 
Test Method
Sequencing and CNV Detection via NextGen Sequencing using PG-Select Capture Probes| Test Code | Test Copy Genes | Test CPT Code | Gene CPT Codes Copy CPT Code | Base Price | |
|---|---|---|---|---|---|
| 4959 | CHM | 81479 | 81479,81479 | $990 | Order Options and Pricing |
Pricing Comments
Testing run on PG-select capture probes includes CNV analysis for the gene(s) on the panel but does not permit the optional add on of exome-wide CNV analysis. Any of the NGS platforms allow reflex to other clinically relevant genes, up to whole exome or whole genome sequencing depending upon the base platform selected for the initial test.
An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.
This test is also offered via a custom panel (click here) on our exome or genome backbone which permits the optional add on of exome-wide CNV or genome-wide SV analysis.
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
Choroideremia (CHM; OMIM# 303100) is an X-linked retinal dystrophy characterized by progressive degeneration of the choriocapillaris, retinal pigment epithelium and photoreceptors (Coussa et al. Ophthalmic Genet 33(2):57-65, 2012; MacDonald et al. GeneReviews, 2003). This blinding disorder typically affects males with a progression from nyctalopia (night blindness) in the first or second decades of life to peripheral visual field loss. Central vision is preserved until age 40-50 years in most CHM cases. Carrier females are usually asymptomatic, but progressive chorioretinal degenerations can occur.
Genetics
CHM is inherited in an X-linked manner and caused by mutations in the Rab Escort Protein 1 (REP-1) gene CHM, which has 15 coding exons that encode a protein involved in vesicular trafficking (Cremers et al. Am J Hum Genet 47: 622–628, 1990; Coussa et al., 2012; MacDonald et al., 2003). CHM is the only gene to date known to be associated with choroideremia. Nearly all CHM mutations lead to a null allele or truncated nonfunctional REP-1 protein. The major types of CHM defects are small insertion and deletions (30%), nonsense mutations (25%), partial and whole gene deletions (20%), and splicing mutations (17%) while missense mutations are very rare (2%) (Human Gene Mutation Database). Gross insertions and complex rearrangements have been also reported but are uncommon.
Clinical Sensitivity - Sequencing with CNV PG-Select
Direct sequencing of the 15 exons and adjacent splice sites detects CHM mutations in 60%-95% of affected males (MacDonald et al. GeneReviews, 2003).
Testing Strategy
This test provides full coverage of all coding exons of the CHM gene, plus ~10 bases of flanking noncoding DNA. We define full coverage as >20X NGS reads or Sanger sequencing.
It also includes targeted testing of the deep intronic splicing mutation c.314+10127T>A (van den Hurk et al. Hum Genet 113(3):268-275, 2003).
Indications for Test
Candidates for this test are patients with Choroideremia. Testing is also indicated for family members of patients who have known CHM mutations.
Candidates for this test are patients with Choroideremia. Testing is also indicated for family members of patients who have known CHM mutations.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| CHM | 300390 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Disease
| Name | Inheritance | OMIM ID |
|---|---|---|
| Choroideremia | XL | 303100 |
Related Tests
| Name |
|---|
| Flecked Retina Disorder Panel |
| Retinitis Pigmentosa Panel |
| X-linked Retinitis Pigmentosa (XLRP) and Choroideremia Panel |
Citations
- Coussa, R. et al. (2012). “Choroideremia: a review of general findings and pathogenesis.” Ophthalmic Genet 33(2):57-65. PubMed ID: 22017263
- Cremers, F. et al. (1990). “Deletions in patients with classical choroideremia vary in size from 45 kb to several megabases.” Am J Hum Genet 47(4): 622-628. PubMed ID: 2220804
- Human Gene Mutation Database (Bio-base).
- MacDonald, I. et al. (2003) “Choroideremia.” GeneReviews. PubMed ID: 20301511
- van den Hurk, J. et al. (2003). "Novel types of mutation in the choroideremia (CHM) gene: a full-length L1 insertion and an intronic mutation activating a cryptic exon." Hum Genet 113(3):268-275. PubMed ID: 12827496
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
Loading...
×
ORDER OPTIONS
View Ordering Instructions1) Select Test Type
2) Select Additional Test Options
No Additional Test Options are available for this test.