This test analyzes the AXIN2 gene, which is associated with oligodontia-colorectal cancer syndrome. Individuals with this condition present with oligodontia (defined as congenital agenesis of six or more permanent teeth) in childhood followed by an increased risk of colorectal cancer in adulthood.
Analysis of this gene may confirm a diagnosis and help guide treatment and management decisions. Identification of a disease-causing variant would also guide testing and diagnosis of at-risk relatives. This test is specifically designed for heritable germline mutations and is not appropriate for the detection of somatic mutations in tumor tissue.
AXIN2 can also be ordered as part of a larger panel to test for different types of hereditary cancer conditions. Depending on the individual’s clinical and family history, one of these larger panels may be appropriate. Any of these larger panels can be ordered at no additional charge.
The AXIN2 gene is essential for the development of permanent teeth. Oligodontia, defined as the congenital agenesis of six or more permanent teeth, is relatively rare. It can occur in isolation but is most often associated with other congenital anomalies. Pathogenic variants AXIN2 are known to cause oligodontia. Recent evidence has also found that individuals with such variants are also predisposed to developing colon adenomas, polyps, and colorectal cancer. This condition is called oligodontia-colorectal cancer syndrome. Affected individuals may present with oligodontia and/or colorectal cancer; the risks for each is currently unclear.
Individuals with a pathogenic variant in AXIN2 have an increased risk of malignancy compared to the average person. However, not everyone with such a variant will actually develop cancer. Further, the same variant can present differently, even among family members. Because we cannot predict which cancers may develop, most who are found to have a pathogenic variant will be offered screening tests to detect and prevent cancer. The precise colorectal cancer risks associated with AXIN2 pathogenic variants is currently unknown because the number of reported cases is limited.
Oligodontia-colorectal cancer syndrome is inherited in an autosomal dominant pattern.
The prevalence of oligodontia-colorectal cancer syndrome is currently unknown.
Invitae is a College of American Pathologists (CAP)-accredited and Clinical Laboratory Improvement Amendments (CLIA)-certified clinical diagnostic laboratory performing full-gene sequencing and deletion/duplication analysis using next-generation sequencing technology (NGS).
Our sequence analysis covers clinically important regions of each gene, including coding exons, +/- 10 base pairs of adjacent intronic sequence in the transcript listed below. In addition, analysis covers the select non-coding variants specifically defined in the table below. Any variants that fall outside these regions are not analyzed. Any specific limitations in the analysis of these genes are also listed in the table below.
Based on validation study results, this assay achieves >99% analytical sensitivity and specificity for single nucleotide variants, insertions and deletions <15bp in length, and exon-level deletions and duplications. Invitae's methods also detect insertions and deletions larger than 15bp but smaller than a full exon but sensitivity for these may be marginally reduced. Invitae’s deletion/duplication analysis determines copy number at a single exon resolution at virtually all targeted exons. However, in rare situations, single-exon copy number events may not be analyzed due to inherent sequence properties or isolated reduction in data quality. Certain types of variants, such as structural rearrangements (e.g. inversions, gene conversion events, translocations, etc.) or variants embedded in sequence with complex architecture (e.g. short tandem repeats or segmental duplications), may not be detected. Additionally, it may not be possible to fully resolve certain details about variants, such as mosaicism, phasing, or mapping ambiguity. Unless explicitly guaranteed, sequence changes in the promoter, non-coding exons, and other non-coding regions are not covered by this assay. Please consult the test definition on our website for details regarding regions or types of variants that are covered or excluded for this test. This report reflects the analysis of an extracted genomic DNA sample. In very rare cases, (circulating hematolymphoid neoplasm, bone marrow transplant, recent blood transfusion) the analyzed DNA may not represent the patient's constitutional genome.
|Gene||Transcript reference||Sequencing analysis||Deletion/Duplication analysis|