APC Sequencing and Deletion/Duplication

This test is used to identify individuals with a suspected diagnosis of familial adenomatous polyposis (FAP) and attenuated familial adenomatous polyposis (AFAP). It analyzes single-nucleotide variants, deletions, and duplications in the APC gene. Sample reports and information regarding the specific variants analyzed for each gene are available on our website QuestHereditaryCancer.com.

If a familial mutation has been detected by sequencing or deletion/duplication studies, the Hereditary Cancer Single Site(s) test (test code 93945) may be considered. Official test results of the family member must be available for laboratory review. For more information, please visit our website QuestHereditaryCancer.com. To discuss a family history with a Quest Diagnostics genetic counselor, please call Quest Genomics Client Services at 1.866.GENE.INFO (1.866.436.3463).

Generally, this test may be appropriate for individuals with a personal or family history of ≥ 20 colorectal adenomas, colorectal cancer, duodenal adenomas, duodenal cancer, papillary thyroid cancer, hepatoblastoma, desmoid tumor, or multifocal congenital hypertrophy of the retinal pigment epithelium (CHRPE).¹

Informed consent following genetic counseling is strongly recommended. Whenever possible, consider testing the person in the family with the youngest age at the time of diagnosis of an FAP- or AFAP-associated cancer or polyps.

For more information or to discuss a family history with a Quest genetic counselor, please call
Quest Genomics Client Services at 1.866.GENE.INFO (1.866.436.3463).

The right time is different for every individual. An individual’s current medical status, personal experience with symptoms of FAP, treatment or screening plane, and general readiness for genetic information all influence the decision to be tested. Having an open dialogue with individuals about these topics can assist with shared decision-making.

Upon receipt of a fully completed order, our team will verify coverage with your patient’s healthcare insurance plan and estimate their likely out-of-pocket responsibility. If your patient’s estimated responsibility is over $100, we will notify you and/or your patient prior to test initiation to discuss options for continuation or cancellation of the test. Please note that orders lacking complete information will not be processed.

On average, results will be completed 14 to 21 days after receipt of the sample in the laboratory if the family history form and order are complete and the health plan does not require preauthorization. Turnaround time may vary based on delays caused by incomplete orders or insurance authorizations.

Individuals with a positive result have a pathogenic or likely pathogenic variant detected in the APC gene. This individual has a diagnosis of FAP or AFAP, but a positive result does not mean that an individual has polyps or cancer. Specific risk information will be provided in the result report, and you can visit our website at QuestHereditaryCancer.com for more information.

The National Comprehensive Cancer Network (NCCN^®) provides up-to-date surveillance and management recommendations for individuals with a positive result.¹

A negative result means that a pathogenic or likely pathogenic variant was not detected in the APC gene. For more information regarding specific genetic variants analyzed in this assay, please refer to the methods and limitations section of the genetic testing report. Implications of this result depend on the situation:

Individual with previously diagnosed cancer or polyps: An individual’s risk of recurrence or a related new cancer is based on their personal and family histories of polyps and cancer. In some instances, it may be appropriate to test for other hereditary forms of polyps and/or cancer. Please call Quest Genomics Client Services at 1.866.GENE.INFO (1.866.436.3463) to discuss possible additional studies with a genetic counselor.

Individual without previously diagnosed cancer or polyps but with a family history of cancer polyps: An individual’s risk of polyps or cancer is based on their personal and family histories. Testing an affected family member may further inform this risk assessment. In some instances, it may be appropriate to test for other hereditary forms of polyps and/or cancer. Please call Quest Genomics Client Services at 1.866.GENE.INFO (1.866.436.3463) to discuss possible additional studies with a genetic counselor.

A VUS result means that the variant has not been previously described in the literature or that the clinical significance is unclear based upon currently available evidence. Medical management decisions should be based on personal and family history. Family studies may help to learn more about the clinical significance of this variant. The classification and interpretation of the variant(s) identified reflect the current state of Quest’s understanding at the time of the report. Variant classification and interpretation are subject to professional judgment and may change for a variety of reasons including, but not limited to, updates in classification guidelines and availability of additional scientific and clinical information. It is important to check in with the laboratory annually for variant updates because new information regarding the variant and classification may become available over time. Please visit QuestDiagnostics.com/VariantIQ for information about variant classification. If you have questions, please call Quest Genomics Client Services at 1.866.GENE.INFO (1.866.436.3463) to speak with a genetic counselor.