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Laboratory Test Directory

CTNNB1 (Beta-Catenin) Exon 3 Sequencing

Components

Name Method Department Units
CTNNB1 (Beta-Catenin) Exon 3 Sequencing DNA extraction
Polymerase chain reaction (PCR)
Sanger sequencing
Molecular Genetics

Specimen Requirements

Tissue (Fresh)

Container Type Container Size Specimen Volume
Preferred

Tissue culture transport media

N/A 5mm x 5mm or larger
Alternate

Ringer's lactate solution in sterile container

N/A 5mm x 5mm or larger
Alternate

Sterile container with saline

N/A 5mm x 5mm or larger
Stability

Room temperature - 24 hour(s)
Refrigerated - 48 hour(s)

Specimen Preparation

  • Keep at room temperature or refrigerate
  • Transport to laboratory as soon as possible
  • Do not add fixative
  • Wrap specimen container tightly with parafilm
  • Tumor sample must contain a minimum of 40% tumor

Paraffin embedded tissue

Container Type Container Size Specimen Volume
Preferred

Paraffin block

N/A 5mm x 5mm or larger
Stability

Room temperature - 6 month(s)

Specimen Preparation

  • Keep at room temperature
  • Protect from heat
  • Tumor sample must contain a minimum of 40% tumor

Tissue (Snap-frozen)

Container Type Container Size Specimen Volume
Preferred

Tissue cassette

N/A 5mm x 5mm or larger
Alternate

Cryogenic tube

N/A 5mm x 5mm or larger
Stability

Frozen - 12 month(s)

Specimen Preparation

  • Keep frozen
  • Freeze immediately after collection.
  • Protect from heat
  • Transport to laboratory as soon as possible
  • Tumor sample must contain a minimum of 40% tumor

Tissue scrolls (FFPE)

Container Type Container Size Specimen Volume
Preferred

Sterile container

N/A 10 scrolls
Stability

Room temperature - 6 month(s)

Specimen Preparation

  • Must accompany H&E slide from the same tissue block used to make FFPE scrolls
  • Tumor sample must contain a minimum of 40% tumor

Tissue scrolls (OCT)

Container Type Container Size Specimen Volume
Preferred

Cryogenic tube

N/A 10 scrolls
Stability

Frozen - 12 month(s)

Specimen Preparation

  • Keep frozen
  • Immediately place on dry ice and transport frozen
  • Protect from heat
  • Transport to laboratory as soon as possible
  • Tumor sample must contain a minimum of 40% tumor
  • Must accompany H&E slide from the same OCT-embedded tissue used to make OCT tissue scrolls

OCT-embedded tissue

Container Type Container Size Specimen Volume
Preferred

Tissue cassette

N/A 5mm x 5mm or larger
Alternate

Cryogenic tube

N/A 5mm x 5mm or larger
Stability

Frozen - 12 month(s)

Specimen Preparation

  • Freeze immediately after collection.
  • Keep frozen
  • Protect from heat
  • Transport to laboratory as soon as possible
  • Tumor sample must contain a minimum of 40% tumor

Reasons for Rejection

  • Inadequate tissue
  • Delayed or improper handling
  • Tissue degradation
  • Insufficient tumor content in tumor sample
  • Wrong type of specimen

Comments

Please click on the Lab Form link in the Forms Section to print and complete the Pediatric Oncology Test Requisition Form. Submission of a completed Test Requisition Form is required, and submission of informed consent form is recommended (but not required).

This test is a targeted Sanger sequence analysis of exon 3 of the CTNNB1 gene.

Medulloblastoma is the most common malignant brain tumor in children. Patients with medulloblastoma are stratified in various risk groups (low, intermediate, or high risk) based on a variety of clinical and biological factors. Recently, several molecular subgroups of medulloblastoma have been established based on gene expression signatures. The WNT molecular subgroup is seen in about 10% of medulloblatoma cases, is typically seen in children over the age of 4 years as well as in adults, and is considered as a low-risk group. WNT subgroup is characterized by the tumor harboring an activating, heterozygous somatic variant in the CTNNB1 gene, and the first-tier method used to classify this subgroup is beta-catenin immunohistochemial staining/analysis of the tumor tissue. When immunohistochemical result is positive for beta-catenin immunoreactivity, then molecular genetic testing of the CTNNB1 gene can be used to confirm the WNT subgroup classification. All of the CTNNB1 variants described to date in medulloblatoma are heterozygous, missense variants that occur in exon 3 of this gene that impact amino acid residues 32, 33, 34, 35, and 37. Therefore, targeted sequence analysis of CTNNB1 exon 3 can be used to help distinguish the WNT subgroup from non-WNT subgroup of medulloblatoma.

Medulloblatoma tumors that are positive for beta-catenin immunoreactivity, positive for an activating variant in exon 3 of the CTNNNB1 gene, and negative for MYCN and MYC amplification by FISH analyses are considered to be low risk. Therefore, in addition to CTNNB1 exon 3 sequencing, FISH analyses for MYCN and MYC amplification are also recommended to evaluate for the risk classification for patients with medulloblatoma.

For questions and more information, please call (614) 722-2866.

Forms

Lab Form

CPT Code

  • 81403