Using Genetic Testing to Predict Disease and More

Predictive Testing

Predictive genetic testing evaluates a person’s DNA to identify specific gene mutations that may increase their risk of developing certain diseases in the future. This type of testing is typically recommended for individuals with a family history of genetic conditions, such as breast cancer, Huntington’s disease, or Alzheimer’s. There are two main categories: 

• Presymptomatic testing detects mutations that will almost certainly lead to disease if the person lives long enough. 

• Predispositional testing identifies mutations that increase the likelihood of developing a condition, but do not guarantee it. The process begins with genetic counseling, followed by a DNA sample collection — usually through blood or saliva — and laboratory analysis focused on known risk-related genes. 

Once results are available, a genetic counselor interprets the findings and discusses their implications. A positive result may prompt proactive health measures like increased screenings, lifestyle changes, or preventive treatments. For example, someone with a BRCA1 mutation might opt for earlier mammograms or even risk-reducing surgery. A negative result means the specific mutation wasn’t found, but it doesn’t eliminate all risk. In some cases, results may show a variant of uncertain significance (VUS), which requires ongoing research and monitoring. Predictive testing empowers individuals to make informed decisions about their health long before symptoms appear. 

Carrier Screening 

Carrier genetic testing identifies whether an individual carries a gene mutation that could be passed on to their biological children, potentially causing inherited disorders. Most commonly, it screens for autosomal recessive conditions, where both parents must carry the same mutated gene for a child to be affected. The test typically involves analyzing a blood, saliva, or cheek swab sample to detect specific gene variants. Carriers usually show no symptoms themselves because they have one normal copy of the gene that compensates for the mutated one. If both partners are carriers of the same condition, each child has a 25% chance of inheriting the disorder, a 50% chance of being a carrier, and a 25% chance of inheriting two normal genes.

Carrier screening is especially recommended before pregnancy to help couples understand their reproductive risks and explore options like IVF with genetic testing, sperm or egg donors, or adoption. Expanded carrier screening can test for hundreds of conditions, while targeted screening focuses on disorders more common in certain ethnic groups or family histories. A negative result lowers the likelihood of passing on a condition but doesn’t eliminate it, as not all mutations are detectable. Genetic counseling is often provided to help interpret results and guide family planning decisions. 

Is Genetic Testing Right for You? 

Genetic testing can be a valuable tool for individuals seeking to understand their health risks, make informed medical decisions, or plan for their family’s future. This allows for proactive steps such as lifestyle changes, early screenings, or targeted treatments. It’s especially helpful for those with a family history of genetic illnesses or those considering pregnancy. However, testing should be approached thoughtfully, ideally with guidance from a genetic counselor to interpret results and consider emotional, ethical, and privacy implications.