Niemann-Pick Disease Type C via the NPC2 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 | |
|---|---|---|---|---|---|
| 7763 | NPC2 | 81404 | 81404,81479 | $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
Niemann-Pick disease type C (NPC) is a storage lipid disorder in which defects in the intracellular transport and trafficking of low-density lipoprotein (LDL)-derived cholesterol result in the accumulation of cholesterol and other lipids in tissues. NPC is characterized by an extensive clinical heterogeneity with regards to the age of onset, initial symptoms, severity, and progression. NPC can present at any time from intrauterine to the sixth decade with liver failure, incidental organomegaly, or a wide variety of neurological and psychiatric symptoms. Most common clinical features include enlarged spleen and liver, jaundice, dystonia, seizures, tremor, ataxia, vertical supranuclear gaze palsy, learning difficulty, and slurred speech (Patterson, Neurologist 9:301-310, 2003; Vanier and Millat Clin Genet 64:269-281, 2003). Cases with fetal onset, detected ultrasonically in the form of severe ascites, were reported (Maconochie et al. Arch Dis Child 64:1391-1393, 1989; Manning et al. Arch Dis Child 65:335-336, 1990; Spiegel et al. Am J Med Genet 149A:446-450, 2009). NPC occurs worldwide; however, it is more common in two genetic isolates. The first isolate is a French population from Normandy, who settled in Nova Scotia (Millat et al. Am J Hum Genet 65:1321-1329, 1999); the second is a Hispanic population from the Upper Rio Grande Valley in the United States, who settled in New Mexico and Colorado (Wenger et al. Am J Dis Child 131:955-961, 1977).
Genetics
NPC is inherited with an autosomal recessive manner and is further divided into two subtypes, NPC1 and NPC2, based on the causative gene. Clinically, NPC1 and NPC2 are identical. NPC2 (OMIM 607625) is caused by variants in the NPC2 gene (Naureckiene et al. Science 290:2298-2301, 2000). To date, ~18 different variants have been reported in patients with variable ethnic background. Variants included missense, nonsense, frameshift, small insertions, and splicing. The NPC2 gene encodes a soluble lysosomal protein with cholesterol binding properties; it is required for the egress of lipids from the lysosomes
Clinical Sensitivity - Sequencing with CNV PG-Select
This test detects nearly 100 % of NPC2 sequence variants (Patterson, GeneReviews, 2008), which are responsible for ~ 4% of individuals with NPC (Park et al. Hum Mutat 22:313-325, 2003).
Testing Strategy
This test provides full coverage of all coding exons of the NPC2 gene, plus ~10 bases of flanking noncoding DNA. We define full coverage as >20X NGS reads or Sanger sequencing.
Indications for Test
Patients with clinical features suggestive of NPC and with no variants in the NPC1 gene. Candidates for this test may include: (1) Patients with unexplained dementia or psychiatric illness and cognitive impairment, particularly when accompanied by ataxia, dystonia, or vertical supranuclear gaze palsy; (2) infants with unexplained cholestatic jaundice; and (3) older children with progressive liver disease (Patterson, Neurologist 9:301-310, 2003). This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in NPC2.
Patients with clinical features suggestive of NPC and with no variants in the NPC1 gene. Candidates for this test may include: (1) Patients with unexplained dementia or psychiatric illness and cognitive impairment, particularly when accompanied by ataxia, dystonia, or vertical supranuclear gaze palsy; (2) infants with unexplained cholestatic jaundice; and (3) older children with progressive liver disease (Patterson, Neurologist 9:301-310, 2003). This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in NPC2.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| NPC2 | 601015 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Disease
| Name | Inheritance | OMIM ID |
|---|---|---|
| Niemann-Pick Disease Type C2 | AR | 607625 |
Related Test
| Name |
|---|
| Niemann-Pick Disease Type C Panel |
Citations
- Maconochie, I. K., et.al. (1989). "Fetal ascites: an unusual presentation of Niemann-Pick disease type C." Arch Dis Child 64(10 Spec No): 1391-3. PubMed ID: 2589877
- Manning, D. J., et.al. (1990). "Fetal ascites: an unusual presentation of Niemann-Pick disease type C." Arch Dis Child 65(3): 335-6. PubMed ID: 2334227
- Marc Patterson (2008). "Niemann-Pick Disease Type C." PubMed ID: 20301473
- Millat, G., et.al. (1999). "Niemann-Pick C1 disease: the I1061T substitution is a frequent mutant allele in patients of Western European descent and correlates with a classic juvenile phenotype." Am J Hum Genet 65(5): 1321-9. PubMed ID: 10521297
- Naureckiene, S., et.al. (2000). "Identification of HE1 as the second gene of Niemann-Pick C disease." Science 290(5500): 2298-301. PubMed ID: 11125141
- Park, W. D., et.al. (2003). "Identification of 58 novel mutations in Niemann-Pick disease type C: correlation with biochemical phenotype and importance of PTC1-like domains in NPC1." Hum Mutat 22(4): 313-25. PubMed ID: 12955717
- Patterson, M. C. (2003). "A riddle wrapped in a mystery: understanding Niemann-Pick disease, type C." Neurologist 9(6): 301-10. PubMed ID: 14629784
- Spiegel, R., et.al. (2009). "The clinical spectrum of fetal Niemann-Pick type C." Am J Med Genet A 149A(3): 446-50. PubMed ID: 19206179
- Vanier, M. T., Millat, G. (2003). "Niemann-Pick disease type C." Clin Genet 64(4): 269-81. PubMed ID: 12974729
- Wenger, D. A., et.al. (1977). "Nine cases of sphingomyelin lipidosis, a new variant in Spanish-American Children. Juvenile variant of Niemann-Pick Disease with foamy and sea-blue histiocytes." Am J Dis Child 131(9): 955-61. PubMed ID: 900082
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
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