In addition to sequencing using genomic sequencing (“next generation sequencing” or NGS), a range of other testing methodologies* may be needed to identify pathogenic changes in the genes in the panel including:
- Sanger sequencing
- long range PCR
- copy number analysis
- methylation analysis (e.g. MLH1 epimutation)
- analysis for structural rearrangements (e.g. MSH2 inversion).
* Note: all panels may not have uniform coverage of all exons and promoter regions. Therefore if testing for GAPPS, request testing through a laboratory which offers promoter testing.
Information about DNA tests and testing laboratories is available from:
A variant-specific test (rather than sequencing a single gene or gene panel) may be more appropriate and cost effective where a relative is known to have a germline pathogenic variant or a pathogenic variant has been identified in the patient’s tumour.
If these genes are tested using genomic sequencing (“next generation sequencing” or NGS), and testing has not identified a pathogenic variant, the value of testing using another methodology should be considered.
With multiple adenomas phenotype in the absence of a germline APC pathogenic variant, can consider testing multiple polyps for APC mosaicism.