Genetic testing can reveal whether you carry gene changes linked to disease, how your body processes certain medications, your risk of developing specific cancers, and whether you could pass inherited conditions to your children. The results fall into several distinct categories depending on the type of test, and understanding what each one actually tells you is the key to making sense of them.
How Results Are Classified
Every genetic test result places each gene change (called a variant) into one of a few categories. A pathogenic variant is one known to cause or contribute to a health condition. A benign variant is a harmless change that doesn’t affect your health. Between those two extremes sits the variant of uncertain significance, or VUS, which means the lab found a change in your DNA but doesn’t yet know whether it matters.
A VUS result is more common than most people expect. In multi-gene panel testing, roughly 33% of results come back inconclusive because of a VUS. Whole exome or genome sequencing produces a slightly lower rate, around 23%. If you receive a VUS, it doesn’t mean something is wrong. It means the science hasn’t caught up yet. Testing other family members can sometimes clarify whether the variant tracks with disease in your relatives. Over time, as more data accumulates, many VUS results get reclassified as either pathogenic or benign.
Diagnosing a Current Condition
When you already have symptoms, genetic testing can confirm or rule out a suspected condition. This is diagnostic testing. A child with unexplained developmental delays, for instance, might undergo testing to identify a chromosomal difference or a single-gene disorder. An adult with a family history of a neurological condition who starts showing symptoms might get tested for that specific gene change.
Diagnostic results are typically the most straightforward: either the variant explaining the symptoms is found, or it isn’t. A positive result can end a long diagnostic journey, guide treatment decisions, and alert family members who may carry the same variant. A negative result doesn’t always mean there’s no genetic cause. It may simply mean current testing technology didn’t detect one.
Predicting Future Disease Risk
Predictive or screening tests estimate your risk of developing a condition before symptoms appear. This is fundamentally different from diagnostic testing because a positive result doesn’t mean you have or will definitely develop the disease. It means your risk is higher than average.
Cancer risk genes are the most well-known example. Women who inherit a harmful change in the BRCA1 or BRCA2 gene have a greater than 60% lifetime chance of developing breast cancer, compared to about 13% in the general population. For ovarian cancer, the gap is even more dramatic: 39% to 58% lifetime risk with a BRCA1 change, versus about 1.1% in the general population. BRCA2 carriers face a 13% to 29% ovarian cancer risk.
These numbers are powerful, but they’re probabilities, not certainties. Knowing your status lets you and your healthcare team make informed decisions about screening schedules, preventive options, and lifestyle factors that may lower your risk.
Carrier Status for Inherited Conditions
Carrier screening tells you whether you carry one copy of a gene change for a recessive condition. Carriers are healthy themselves because they have a second, working copy of the gene. But if both parents carry a change in the same gene, each pregnancy has a 25% chance of producing a child with the condition.
The most commonly screened conditions include cystic fibrosis, spinal muscular atrophy, and sickle cell disease. Cystic fibrosis affects about 1 in 2,500 people in non-Hispanic white populations, with lower rates in other groups. It progressively damages the lungs, pancreas, and digestive system, with a current median predicted survival of about 42 years. The sensitivity of carrier screening varies by ethnicity, ranging from under 50% in people of Asian ancestry to 94% in those of Ashkenazi Jewish descent.
Spinal muscular atrophy causes degeneration of motor neurons in the spinal cord, leading to muscle weakness and atrophy. Carrier testing measures the number of copies of the responsible gene. Sickle cell screening uses blood tests alongside genetic analysis to identify carriers of the trait. For couples planning a pregnancy, carrier screening provides information that can shape reproductive decisions and preparation.
Prenatal and Newborn Screening
During pregnancy, noninvasive prenatal testing (NIPT) analyzes fragments of fetal DNA circulating in the mother’s blood. It primarily screens for Down syndrome (an extra copy of chromosome 21), trisomy 18, trisomy 13, and differences in the number of X and Y chromosomes. Some panels also look for missing or duplicated sections of chromosomes. NIPT is a screening test, not a diagnostic one, so a positive result typically leads to a confirmatory test like amniocentesis.
After birth, every state screens newborns for a panel of conditions recommended by the Department of Health and Human Services. The Recommended Uniform Screening Panel includes over 30 core conditions spanning several categories: organic acid disorders, fatty acid processing problems, amino acid disorders like phenylketonuria, endocrine conditions like congenital hypothyroidism, hemoglobin disorders including sickle cell disease, cystic fibrosis, spinal muscular atrophy, severe combined immunodeficiency, and others. These conditions are included because early detection paired with treatment can prevent serious disability or death. A heel prick blood sample collected in the first day or two of life is all it takes.
How Your Body Handles Medications
Pharmacogenomic testing reveals how your genetic makeup affects the way you metabolize specific drugs. Some people break down medications much faster or slower than average because of variations in liver enzymes responsible for processing those drugs.
The practical impact is significant. If you’re a slow metabolizer of certain antidepressants, the drug builds up to higher levels in your blood, increasing the risk of side effects. The FDA maintains a table of gene-drug interactions that includes dozens of medications. Several common antidepressants and antipsychotic medications require dose adjustments for people who metabolize them slowly. Blood thinners are another major category: the common antiplatelet drug clopidogrel works by being converted into its active form in your body, and people who metabolize it poorly may not get adequate protection against blood clots. Warfarin dosing is influenced by at least three different genetic variations.
This type of testing is especially useful if you’ve had unexpected side effects from medications, if a drug didn’t seem to work at standard doses, or if you’re starting a medication with a narrow margin between an effective dose and a harmful one.
What Genetic Testing Does Not Show
Genetic testing has real limits. Most common diseases, like type 2 diabetes or heart disease, result from the combined effect of many genes interacting with diet, exercise, stress, and other environmental factors. A genetic test can identify certain risk variants, but it can’t account for the full picture.
Direct-to-consumer tests sold online have additional limitations. These tests typically use a different technology than clinical-grade sequencing, looking only at specific known variants rather than reading entire genes. While a majority of variant findings in these tests have been confirmed as accurate, the context around interpretation matters. A clinical test ordered by a healthcare provider includes expert analysis of your results alongside your personal and family medical history, which a consumer report can’t replicate.
How Long Results Take
Turnaround time depends on the complexity of the test. Small single-gene tests or targeted panels generally return results in 2 to 6 weeks. Larger tests like whole exome or whole genome sequencing can take several months. NIPT results during pregnancy typically come back on the faster end, often within one to two weeks. If you’re waiting on results, your ordering provider or genetic counselor can usually give you a more specific timeline based on the lab being used.