17 Jul CNV testing should be universally used in clinical genetic testing
Your DNA holds instructions for everything your body needs to do, from determining the color of your eyes to breaking down medications. Each person’s genome is a unique combination of DNA sequences and structural variations that play major roles in determining who we are. Structural variations such as Copy Number Variants (CNV) involve alterations in the number of copies of specific regions of DNA, which can either be deleted or duplicated.
Some of these deletions and duplications can be pathogenic and contribute to disease. A recent study from Invitae published in the journal Genetics in Medicine, shows the importance of routinely including deletion and duplication detection in genetic testing. Approximately 10% of patients with genetic changes associated with disease show Copy Number Variant changes that may go undetected by traditional approaches. The findings are based on the largest analysis to date of genetic testing to identify deletions and duplications involving single genes using next-generation sequencing (NGS) techniques. The study found that these structural changes (or CNVs) are present in a substantial number of patients and suggested that CNV testing should be universally used in clinical genetic testing. With few exceptions, these types of exonic CNVs are not typically detectable or reported from cytogenetic methods such as whole-genome chromosomal microarrays.
Detecting structural changes with CNVs is also important for precision prescribing. Using CNVs for certain genes can identify people at risk of adverse drug reactions and optimize medication regimens. Pharmacogenetic tests that only detect changes in DNA sequences (such as SNPs), may classify individuals incorrectly since they are not able to detect changes in the number of copies of the gene and may result in unsafe and ineffective treatment options. Comprehensive panels that include sequence variations (SNPs), as well as structural changes (CNVs), should be the standard of care.