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Test ID: APCZ APC Gene, Full Gene Analysis, Varies

Useful For

Confirmation of familial adenomatous polyposis (FAP) diagnosis for patients with clinical features

Additional Tests

Test ID Reporting Name Available Separately Always Performed
COLAB Hereditary Colon Cancer CGH Array Yes, (order FMTT) Yes

Testing Algorithm

When this test is ordered, comparative genomic hybridization will always be performed at an additional charge.


See Colonic Polyposis Syndromes Testing Algorithm in Special Instructions.

Method Name

Custom Sequence Capture and Targeted Next-Generation Sequencing

COLAB: Array Comparative Genomic Hybridization (aCGH)

Reporting Name

APC Gene, Full Gene Analysis

Specimen Type


Ordering Guidance

This test should be ordered only for individuals with symptoms suggestive of familial adenomatous polyposis (FAP). Asymptomatic patients with a family history of FAP should not be tested until a variant has been identified in an affected family member.

Shipping Instructions

Specimen preferred to arrive within 96 hours of collection.

Specimen Required

Patient Preparation: A previous bone marrow transplant from an allogenic donor will interfere with testing. Call 800-533-1710 for instructions for testing patients who have received a bone marrow transplant.

Specimen Type: Whole blood


Preferred: Lavender top (EDTA) or yellow top (ACD)

Acceptable: Any anticoagulant

Specimen Volume: 3 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send specimen in original tube.

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Ambient (preferred)

Clinical Information

Familial adenomatous polyposis (FAP) is an autosomal dominant condition caused by alterations in the APC gene located on the long arm of chromosome 5 (5q21). Classic FAP is characterized by progressive development of hundreds to thousands of adenomatous colon polyps. Polyps may develop during the first decade of life, and the majority of untreated FAP patients will develop colon cancer by age 40. Typically, there is a predominance of polyps on the left side of the colon; however, other areas of the colon may also be affected. The presence of extracolonic manifestations is variable and includes gastric and duodenal polyps, ampullary polyps, osteomas, dental abnormalities (unerupted teeth), congenital hypertrophy of the retinal pigment epithelium (CHRPE), benign cutaneous lesions, desmoids tumors, hepatoblastoma, and extracolonic cancers. Common constellations of colonic and extracolonic manifestations have resulted in the designation of 3 clinical variants: Gardner syndrome, Turcot syndrome, and hereditary desmoid disease.


Gardner syndrome is characterized by colonic polyps of classic FAP with epidermoid skin cysts and benign osteoid tumors of the mandible and long bones.


Turcot syndrome is characterized by multiple colonic polyps and central nervous system (CNS) tumors. Turcot syndrome is an unusual clinical variant of FAP, as it is also considered a clinical variant of hereditary nonpolyposis colorectal cancer (HNPCC). Individuals with Turcot syndrome have CNS tumors in addition to adenomatous polyps. The types of CNS tumor observed helps to distinguish Turcot-FAP variant patients from Turcot-HNPCC variant patients. The predominant CNS tumor associated with the Turcot-FAP variant is medulloblastoma, while glioblastoma is the predominant CNS tumor associated with Turcot-HNPCC.


Hereditary desmoid disease (HDD) is a variant of FAP with multiple desmoids tumors as the predominant feature. Many patients with HDD may not even show colonic manifestations of FAP. APC germline testing may assist clinicians in distinguishing a sporadic desmoid tumor from that associated with FAP.


Attenuated FAP (AFAP) is characterized by later onset of disease and a milder phenotype (typically <100 adenomatous polyps and fewer extracolonic manifestations) than classic FAP. Typically individuals with AFAP develop symptoms of the disease at least 10 to 20 years later than classically affected individuals. Individuals with AFAP often lack a family history of colon cancer and/or multiple adenomatous polyps. Of note, clinical overlap is observed between AFAP and MYH-associated polyposis (MAP), an autosomal recessive polyposis syndrome typically associated with fewer than 100 polyps. Although the clinical phenotype of MAP remains somewhat undefined, extracolonic manifestations, including CHRPE have been described in affected patients. Given the phenotypic overlap of AFAP and MAP, these tests are commonly ordered together or in a reflex fashion.


See Colonic Polyposis Syndromes Testing Algorithm in Special Instructions for additional information.

Reference Values

An interpretive report will be provided.


All detected alterations are evaluated according to American College of Medical Genetics and Genomics (ACMG) recommendations.(1) Variants are classified based on known, predicted, or possible pathogenicity and reported with interpretive comments detailing their potential or known significance.

Clinical Reference

1. Richards S, Aziz N, Bale S, et al: Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genet Med. 2015 May;17(5):405-424

2. American Society of Clinical Oncology. American Society of Clinical Oncology policy statement update: genetic testing for cancer susceptibility Clin Oncol. 2003;21:2397-2406

3. Half E, Bercovich D, Rozen P: Familial adenomatous polyposis. Orphanet J Rare Dis. 2009 Oct 12;4:22

4. Croner RS, Brueckl WM, Reingruber B, et al: Age and manifestation related symptoms in familial adenomatous polyposis. BMC Cancer. 2005 Mar 2;5:24

Day(s) Performed


Report Available

14 to 20 days

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


Hereditary Colon Cancer CGH Array, additional test


LOINC Code Information

Test ID Test Order Name Order LOINC Value
APCZ APC Gene, Full Gene Analysis 94188-0


Result ID Test Result Name Result LOINC Value
53568 Result Summary 50397-9
53569 Result 82939-0
53570 Interpretation 69047-9
53571 Additional Information 48767-8
53572 Specimen 31208-2
53573 Source 31208-2
53574 Array Billed? No LOINC Needed
53575 Released By 18771-6


1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available in Special Instructions:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Molecular Genetics: Inherited Cancer Syndromes Patient Information (T519) in Special Instructions

3. If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-Oncology Test Request (T729)

-Gastroenterology and Hepatology Client Test Request (T728)

Mayo Clinic Laboratories | Genetics and Pharmacogenomics Catalog Additional Information: