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Hereditary Diffuse Gastric Cancer via the CDH1 Gene

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

Sequencing

Test Code Test Copy GenesIndividual Gene PriceCPT Code Copy CPT Codes
798 CDH1$960.00 81406 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

The clinical sensitivity of CDH1 germline mutations is 30% for HDGC families (Carneiro et al. J Clin Pathol 61:25–30, 2008). The majority of mutations reported to date are single nucleotide substitutions, and small insertions and deletions, which can readily be detected by sequencing. Gross deletions and duplications which can be found in up to 4% of HDGC cases (Kaurah and Huntsman. GeneReviews. 2011) will not be detected using this test.

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Deletion/Duplication Testing via aCGH

Test Code Test Copy GenesIndividual Gene PriceCPT Code Copy CPT Codes
600 CDH1$690.00 81479 Add to Order
Pricing Comment

# of Genes Ordered

Total Price

1

$690

2

$730

3

$770

4-10

$840

11-30

$1,290

31-100

$1,670

Over 100

Call for quote

Turnaround Time

The great majority of tests are completed within 28 days.

Clinical Features

Hereditary diffuse gastric cancer (HDGC) is a highly penetrant diffuse-type of gastric cancer. Patients with HDGC typically present at 40 years of age and have a cumulative cancer risk of 67% by 80 years of age for men and 83% for women (Pharoah et al. Gastroenterology 121:1348–53, 2001). HDGC is caused by CDH1 mutations, which are found in all ethnic groups, but are rare in countries with high rates of sporadic gastric cancer, including Japan and Korea (Guilford et al. Gastric Cancer 13: 1–10, 2010). Approximately 10% of gastric cancers show familial clustering and about 1–3% of cases are known to be hereditary (e.g. CDH1 mutations). Mutations in CDH1 can also cause lobular breast cancer in women (Carneiro et al. J Clin Pathol 61:25–30, 2008).

Genetics

Hereditary diffuse gastric cancer is an autosomal dominant disease that is caused by mutations in the CDH1 gene. CHD1 encodes epithelial cadherin (e-cadherin), which is a transmembrane membrane protein that is responsible for cell-to-cell adhesion and cellular invasion suppression. It also plays important roles in signal transduction, differentiation, gene expression, cell motility, and inflammation (Kaurah and Huntsman. GeneReviews. 2011). The activity of E-cadherin in coordination with the actin cytoskeleton through catenins (e.g. α-, β-, and γ-) is responsible for cellular adhesion. Many human cancers show low levels of e-cadherin compared to normal tissue, which causes defects in cellular adhesion and ultimately leads to metastasis. HDGC is inherited from an affected family member, and de novo mutations haven't been reported. The majority of germline mutations are truncating mutations in e-cadherin, the second hit of the normal allele in normal gastric tissue is usually due to CDH1 promoter hypermethylation and secondly due to CDH1 deletions (Schrader and Huntsman. Cancer Treatment and Research 155: 33-62, 2010).

Testing Strategy

The e-cadherin protein is encoded by 16 exons from the CDH1 gene on chromosome 16q22.1.  Testing is accomplished by amplifying each coding exon and ~20 bp of adjacent noncoding sequence, then determining the nucleotide sequence using standard dideoxy sequencing methods and a capillary electrophoresis instrument. We will also sequence any single exon (Test #100) in family members of patients with a known mutation or to confirm research results.

Indications for Test

The International Gastric Cancer Linkage Consortium (IGCLC) recently made recommendations for testing for HDGC (Fitzgerald, et al. J Med Genet 47(7): 436–444, 2010).

Two gastric cancer cases in family, one individual under age 50 years with confirmed diffuse gastric cancer (DGC) Three confirmed DGC cases in first- or second-degree relatives independent of age Simplex case (i.e., a single occurrence in a family) of DGC occurring before age 40 years Personal or family history of DGC and lobular breast cancer, one diagnosed before age 50 years.

This test is specifically designed for heritable germline mutations and is not appropriate for the detection of somatic mutations in tumor tissue.

Gene

Official Gene Symbol OMIM ID
CDH1 192090
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID
Hereditary Diffuse Gastric Cancer 137215

Related Tests

Name
Cancer Sequencing and Deletion/Duplication Panel
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Hereditary Breast and Ovarian Cancer Syndrome - HBOC HIGH RISK Sequencing and Deletion/Duplication Panel

CONTACTS

Genetic Counselors
Geneticist
Citations
  • Carneiro F, Oliveira C, Suriano G, Seruca R. 2007. Molecular pathology of familial gastric cancer, with an emphasis on hereditary diffuse gastric cancer. Journal of Clinical Pathology 61: 25–30. PubMed ID: 17513507
  • Fitzgerald, et al. (2010). PubMed ID: 20591882
  • Guilford P, Humar B, Blair V. 2010. Hereditary diffuse gastric cancer: translation of CDH1 germline mutations into clinical practice. Gastric Cancer 13: 1–10. PubMed ID: 20373070
  • Kaurah and Huntsman. GeneReviews. 2011
  • Kaurah P, Huntsman DG. 2011. Hereditary Diffuse Gastric Cancer. In: Pagon RA, Adam MP, Bird TD, Dolan CR, Fong C-T, and Stephens K, editors. GeneReviews™, Seattle (WA): University of Washington, Seattle. PubMed ID: 20301318
  • Pharoah PDP, Guilford P, Caldas C. 2001. Incidence of gastric cancer and breast cancer in CDH1 (E-cadherin) mutation carriers from hereditary diffuse gastric cancer families. Gastroenterology 121: 1348–1353. PubMed ID: 11729114
  • Schrader K, Huntsman D. 2010. Hereditary Diffuse Gastric Cancer. In: Pasche B, editors. Cancer Genetics, Boston, MA: Springer US, p 33–63. PubMed ID: 20517687
Order Kits
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.

Deletion/Duplication Testing Via Array Comparative Genomic Hybridization

Test Procedure

Equal amounts of genomic DNA from the patient and a gender matched reference sample are amplified and labeled with Cy3 and Cy5 dyes, respectively. To prevent any sample cross contamination, a unique sample tracking control is added into each patient sample. Each labeled patient product is then purified, quantified, and combined with the same amount of reference product. The combined sample is loaded onto the designed array and hybridized for at least 22-42 hours at 65°C. Arrays are then washed and scanned immediately with 2.5 µM resolution. Only data for the gene(s) of interest for each patient are extracted and analyzed.

Analytical Validity

PreventionGenetics' high density gene-centric custom designed aCGH enables the detection of relatively small deletions and duplications within a single exon of a given gene or deletions and duplications encompassing the entire gene. PreventionGenetics has established and verified this test's accuracy and precision.

Analytical Limitations

Our dense probe coverage may allow detection of deletions/duplications down to 100 bp; however due to limitations and probe spacing this cannot be guaranteed across all exons of all genes. Therefore, some copy number changes smaller than 100-300 bp within a targeted large exon may not be detected by our array.

This array may not detect deletions and duplications present at low levels of mosaicism or those present in genes that have pseudogene copies or repeats elsewhere in the genome.

aCGH will not detect balanced translocations, inversions, or point mutations that may be responsible for the clinical phenotype.

Breakpoints, if occurring outside the targeted gene, may be hard to define.

The sensitivity of this assay may be reduced when DNA is extracted by an outside laboratory.

Order Kits

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
  • 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.

SPECIMEN TYPES
WHOLE BLOOD

(Delivery accepted Monday - Saturday)

  • Collect 3 ml -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 ml -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 stable for up to 48 hours.
  • If refrigerated, blood specimen is stable for up to one week.
  • Label the tube with the patient name, date of birth and/or ID number.

DNA

(Delivery accepted Monday - Saturday)

  • Send in screw cap tube at least 5 µg -10 µg of purified DNA at a concentration of at least 20 µg/ml for NGS and Sanger tests and at least 5 µg of purified DNA at a concentration of at least 100 µg/ml for gene-centric aCGH, MLPA, and CMA tests, minimum 2 µg for limited specimens.
  • For requests requiring more than one test, send an additional 5 µg DNA per test ordered when possible.
  • DNA may be shipped at room temperature.
  • Label the tube with the composition of the solute, DNA concentration as well as the patient’s name, date of birth, and/or ID number.
  • We only accept genomic DNA for testing. We do NOT accept products of whole genome amplification reactions or other amplification reactions.

CELL CULTURE

(Delivery preferred Monday - Thursday)

  • PreventionGenetics should be notified in advance of arrival of a cell culture.
  • Culture and send at least two T25 flasks of confluent cells.
  • Some panels may require additional flasks (dependent on size of genes, amount of Sanger sequencing required, etc.). Multiple test requests may also require additional flasks. Please contact us for details.
  • Send specimens in insulated, shatterproof container overnight.
  • Cell cultures may be shipped at room temperature or refrigerated.
  • Label the flasks with the patient name, date of birth, and/or ID number.
  • We strongly recommend maintaining a local back-up culture. We do not culture cells.
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