Genetic testing examines an individual’s DNA to identify changes that may affect health. These tests can help diagnose conditions, assess disease risk, or guide medical decisions. Gene panels offer a focused approach, investigating specific genetic predispositions or conditions. This provides targeted insights, helping healthcare providers understand potential health implications. This article will cover their definition, applications, the testing process, and how results are interpreted.
What is a Gene Panel?
A gene panel is a specialized genetic test that simultaneously analyzes a selected group of genes or specific regions within them. These genes are chosen because they are associated with a particular disease, syndrome, or set of clinical symptoms. Unlike broader genetic tests, such as whole-exome sequencing (WES) or whole-genome sequencing (WGS), which examine a much larger portion of DNA, gene panels focus only on genes relevant to the suspected condition.
This targeted approach offers several advantages. Gene panels are generally more cost-effective and have a faster turnaround time for results compared to more extensive sequencing methods. By concentrating on a predefined set of genes, analysis and interpretation become more efficient, leading to fewer variants of uncertain significance (VUS) being identified. Gene panels can range in size from two to over one thousand genes, depending on the specific condition being investigated.
Why Are Gene Panels Used?
Gene panels serve various purposes in clinical diagnostics, providing focused insights into an individual’s genetic profile. A primary application is diagnosing inherited conditions, especially when symptoms suggest a genetic disorder caused by variants in multiple genes. For example, panels can identify genetic causes for conditions like cystic fibrosis, certain neurological disorders, or cardiovascular diseases. This approach is helpful when a suspected condition might stem from hundreds of different genetic variations, such as in cases of epilepsy.
Gene panels are also widely used for cancer risk assessment, identifying inherited genetic mutations that increase the likelihood of developing specific cancers. Common examples include testing for mutations in BRCA1 and BRCA2 genes, linked to an elevated risk of breast and ovarian cancers, or genes associated with Lynch Syndrome, which increases the risk for colorectal and endometrial cancers. Other genes like PALB2 and CHEK2 are frequently included due to their association with cancer susceptibility.
Another application is pharmacogenomics, where genetic variations can influence how an individual responds to certain medications. By analyzing specific genes, healthcare providers can make informed decisions about drug choices and dosages, optimizing treatment effectiveness and minimizing adverse reactions. Gene panels are also utilized for carrier screening, identifying individuals who carry a gene for a recessive disorder, such as Tay-Sachs disease or sickle cell disease, that could be passed on to their children, even if the carrier does not show symptoms.
The Gene Panel Process
Undergoing a gene panel test begins with a consultation with a healthcare provider, often a genetic counselor or specialist physician. During this initial discussion, the provider explains the test’s purpose, potential outcomes, and addresses any concerns about the process. This ensures the individual understands what information the test may provide.
Following the consultation, a biological sample is collected for analysis. Common sample types are blood or saliva, though a buccal swab (from inside the cheek) or tissue sample may also be used. Once collected, the sample is sent to a specialized laboratory for processing.
In the laboratory, DNA is extracted from the sample. Using advanced sequencing technologies, often referred to as next-generation sequencing, the specific genes on the panel are analyzed. The DNA sequence data is then compared against a reference human genome to identify genetic variations or mutations. Finally, a comprehensive report detailing the findings is generated and sent back to the healthcare provider who ordered the test.
Interpreting Gene Panel Results
Interpreting gene panel results involves understanding different categories of findings and their implications. A “positive result” indicates a pathogenic or likely pathogenic variant was identified in one or more tested genes. This means a genetic change known to cause or significantly increase the risk for a particular condition was found. Such a result can confirm a diagnosis, inform future health management, or guide treatment strategies.
A “negative result” means no pathogenic or likely pathogenic variants were found in the genes included in the panel. This suggests the individual is not affected by a specific disorder, is not a carrier, or does not have an increased risk for a certain disease within the scope of the tested genes. However, a negative result does not rule out all genetic causes outside the specific genes examined.
Sometimes, a “variant of uncertain significance” (VUS) may be identified. A VUS refers to a genetic change whose impact on health is not yet clearly understood. There may not be enough scientific evidence at the time of testing to classify it as pathogenic or benign. Genetic counselors explain these complex results, discussing their potential implications for the individual and their family, and providing support for making informed decisions about health and future medical care.