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Aceruloplasminemia via the CP Gene

  • Summary and Pricing
  • Clinical Features and Genetics
  • Citations
  • Methods
  • Ordering/Specimens
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TEST METHODS

Sequencing

Test Code TestIndividual Gene PriceCPT Code Copy CPT Codes
2033 CP$1220.00 81479 Add to Order
Targeted Testing

For ordering targeted known variants, please proceed to our Targeted Variants landing page.

Turnaround Time

The great majority of tests are completed within 18 days.

Clinical Sensitivity
Clinical sensitivity is problematic as absence of serum ceruloplasmin is mirrored in other disorders including Wilson’s disease. To date, large ceruloplasminemia patient cohort studies have not been performed to assess clinical sensitivity of CP genetic testing. Therefore, clinical sensitivity of this test is currently unknown. Analytical sensitivity should be high because all pathogenic variants reported are detected by this method.

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Clinical Features
Aceruloplasminemia is an iron accumulation disorder resulting in retinal degeneration, diabetes mellitus and neurological disease. Symptom onset occurs between ages 25 and 60 with individuals initially presenting with anemia. Neurologic findings include ataxia and muscle movement impairment including grimacing, blepharospasm, tremors, chorea, and facial/neck dystonia (Kono 2012; Miyajima 2003). Genetic testing is helpful in the differential diagnosis of Aceruloplasminemia from other neurodegeneration with brain iron accumulation (NBIA) disorders including neuroferritinopathy, PLA2G6-associated neurodegeneration as well as copper metabolic disorders (Wilson and Menkes disease), Huntington’s disease, dystonia, and Parkinson’s disease. Treatments for Aceruloplasminemia include iron chelating agents, fresh frozen plasma containing ceruloplasmin, and antioxidants (Miyajima 2003).
Genetics
Aceruloplasminemia is inherited in an autosomal recessive manner through pathogenic variants in the CP gene. Missense mutations leading to impaired secretion, copper incorporation, and enzymatic activity occur throughout the coding region and represent about half of the reported causative variants in the CP gene (Hellman et al. 2002; Hellman et al. 2002). Frameshift, splice site and nonsense variants represent ~30%, 15% and 15% of cases respectively (Kono 2012). No clear genotype-phenotype correlations exist for Aceruloplasminemia (Miyajima 2003).

The CP gene encodes the ceruloplasmin enzyme that is expressed both as a soluble serum and membrane bound protein through alternative splicing and omission of exon 19. Serum ceruloplasmin is involved in iron homeostasis and plays a role in mobilization of iron from tissue stores and transportation across the basolateral surface of enterocytes. Membrane bound ceruloplasmin is present in astrocytes and is thought to serve as an antioxidant in the central nervous system (Kono 2012; Miyajima 2015).
Testing Strategy
This test involves bidirectional sequencing using genomic DNA of all coding exons of the CP gene plus ~20 bp of flanking non-coding DNA on each side. We will also sequence any single exon (Test #100) or pair of exons (Test #200) in family members of patients with known mutations or to confirm research results.
Indications for Test
Candidates for testing have an absence of serum ceruloplasmin, low copper (less than 10µg/dL) and iron (less than 45µg/dL) serum concentration, elevated serum ferritin (850-4000 ng/mL), and increased hepatic iron concentration. MRI scans displaying iron accumulation in the brain are also indicative of disease. Ideal candidates also present with diabetes mellitus, retinal degeneration, anemia, and neurologic disease (Kono 2012).

Gene

Official Gene Symbol OMIM ID
CP 117700
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID
Aceruloplasminemia 604290

Related Tests

Name
Menkes Disease and Hereditary Motor Neuropathy via the ATP7A Gene
Wilson Disease / Hepatolenticular Degeneration via the ATP7B Gene

CONTACTS

Genetic Counselors
Geneticist
Citations
  • Hellman NE. et al. 2002. The Journal of biological chemistry. 277: 1375-80. PubMed ID: 11689569
  • Hellman NE. et al. 2002. The Journal of biological chemistry. 277: 46632-8. PubMed ID: 12351628
  • Kono S. 2012. Current drug targets. 13: 1190-9.  PubMed ID: 22515741
  • Miyajima H. 2015. Neuropathology : official journal of the Japanese Society of Neuropathology. 35: 83-90. PubMed ID: 25168455
  • Miyajima. 2013. Ceruloplasminemia. In: Pagon RA, Adam MP, Bird TD, Dolan CR, Fong C-T, Smith RJ, and Stephens K, editors. GeneReviews™, Seattle (WA): University of Washington, Seattle. PubMed ID: 20301666
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TEST METHODS

Bi-Directional Sanger Sequencing

Test Procedure

Nomenclature for sequence variants was from the Human Genome Variation Society (http://www.hgvs.org).  As required, DNA is extracted from the patient specimen.  PCR is used to amplify the indicated exons plus additional flanking non-coding sequence.  After cleaning of the PCR products, cycle sequencing is carried out using the ABI Big Dye Terminator v.3.0 kit.  Products are resolved by electrophoresis on an ABI 3730xl capillary sequencer.  In most cases, sequencing is performed in both forward and reverse directions; in some cases, sequencing is performed twice in either the forward or reverse directions.  In nearly all cases, the full coding region of each exon as well as 20 bases of non-coding DNA flanking the exon are sequenced.

Analytical Validity

As of March 2016, we compared 17.37 Mb of Sanger DNA sequence generated at PreventionGenetics to NextGen sequence generated in other labs. We detected only 4 errors in our Sanger sequences, and these were all due to allele dropout during PCR. For Proficiency Testing, both external and internal, in the 12 years of our lab operation we have Sanger sequenced roughly 8,800 PCR amplicons. Only one error has been identified, and this was due to sequence analysis error.

Our Sanger sequencing is capable of detecting virtually all nucleotide substitutions within the PCR amplicons. Similarly, we detect essentially all heterozygous or homozygous deletions within the amplicons. Homozygous deletions which overlap one or more PCR primer annealing sites are detectable as PCR failure. Heterozygous deletions which overlap one or more PCR primer annealing sites are usually not detected (see Analytical Limitations). All heterozygous insertions within the amplicons up to about 100 nucleotides in length appear to be detectable. Larger heterozygous insertions may not be detected. All homozygous insertions within the amplicons up to about 300 nucleotides in length appear to be detectable. Larger homozygous insertions may masquerade as homozygous deletions (PCR failure).

Analytical Limitations

In exons where our sequencing did not reveal any variation between the two alleles, we cannot be certain that we were able to PCR amplify both of the patient’s alleles. Occasionally, a patient may carry an allele which does not amplify, due for example to a deletion or a large insertion. In these cases, the report contains no information about the second allele.

Similarly, our sequencing tests have almost no power to detect duplications, triplications, etc. of the gene sequences.

In most cases, only the indicated exons and roughly 20 bp of flanking non-coding sequence on each side are analyzed. Test reports contain little or no information about other portions of the gene, including many regulatory regions.

In nearly all cases, we are unable to determine the phase of sequence variants. In particular, when we find two likely causative mutations for recessive disorders, we cannot be certain that the mutations are on different alleles.

Our ability to detect minor sequence variants, due for example to somatic mosaicism is limited. Sequence variants that are present in less than 50% of the patient’s nucleated cells may not be detected.

Runs of mononucleotide repeats (eg (A)n or (T)n) with n >8 in the reference sequence are generally not analyzed because of strand slippage during PCR and cycle sequencing.

Unless otherwise indicated, the sequence data that we report are based on DNA isolated from a specific tissue (usually leukocytes). Test reports contain no information about gene sequences in other tissues.

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Ordering Options


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.
REQUISITION FORM
  • The first four pages of the requisition form must accompany all specimens.
  • Billing information is on the third and fourth pages.
  • Specimen and shipping instructions are listed on the fifth and sixth pages.
  • All testing must be ordered by a qualified healthcare provider.

SPECIMEN TYPES
WHOLE BLOOD

(Delivery accepted Monday - Saturday)

  • Collect 3-5 ml (5 ml preferred) of whole blood in EDTA (purple top tube) or ACD (yellow top tube). For Test #500-DNA Banking only, collect 10-20 ml of whole blood.
  • For small babies, we require a minimum of 1 ml of blood.
  • Only one blood tube is required for multiple tests.
  • Ship blood tubes at room temperature in an insulated container. Do not freeze blood.
  • During hot weather, include a frozen ice pack in the shipping container. Place a paper towel or other thin material between the ice pack and the blood tube.
  • In cold weather, include an unfrozen ice pack in the shipping container as insulation.
  • At room temperature, blood specimen is good for up to 48 hours.
  • If refrigerated, blood specimen is good for up to one week.
  • Label the tube with the patient name, date of birth and/or ID number.

DNA

(Delivery accepted Monday - Saturday)

  • NextGen Sequencing Tests: Send in screw cap tube at least 10 µg of purified DNA at a concentration of at least 50 µg/ml
  • Sanger Sequencing Tests: Send in a screw cap tube at least 15 µg of purified DNA at a concentration of at least 20 µg/ml. For tests involving the sequencing of more than three genes, send an additional 5 µg DNA per gene. DNA may be shipped at room temperature.
  • Deletion/Duplication via aCGH: Send in screw cap tube at least 1 µg of purified DNA at a concentration of at least 100 µg/ml.
  • Whole-Genome Chromosomal Microarray: Collect at least 5 µg of DNA in TE (10 mM Tris-cl pH 8.0, 1mM EDTA), dissolved in 200 µl at a concentration of at least 100 ng/ul (indicate concentration on tube label). DNA extracted using a column-based method (Qiagen) or bead-based technology is preferred.

CELL CULTURE

(Delivery accepted Monday - Thursday)

  • PreventionGenetics should be notified in advance of arrival of a cell culture.
  • Ship at least two T25 flasks of confluent cells.
  • Label the flasks with the patient name, date of birth, and/or ID number.
  • We do not culture cells.