What Are the Different Kinds of Gene Tests? A Guide to Genetic Testing Options

A “genetic test” can refer to anything from checking one specific change in DNA to examining almost the entire genome. Some tests focus on a single gene, while others compare hundreds of genes at once. Still others look at chromosomes, gene activity, or the proteins produced from genetic instructions. DNA testing is one form of genetic testing that specifically examines DNA.

The easiest way to understand different genetic tests is to separate them into two categories: what the test examines and why the testing is done. Once those two ideas are separated, many of the terms used in genetic testing become much easier to understand.

Genetic Testing Terms to Know

Genetic testing comes with its own vocabulary. These are some of the terms readers will come across in this guide:

What Is Genetic Testing, and Why Are There Different Kinds?

Genetic testing examines genetic material or related biological markers to find particular variations or patterns. Depending on the test, this may involve DNA sequencing, chromosomes, gene activity, proteins, or enzymes. Different genetic tests analyze different types and amounts of genetic material.

There isn't a single test that examines every genetic change in the same way. You may consider a focused test when the question has to do with one variant. You might look at broader testing if several genes could be relevant. The testing method must match the question being asked. (MedlinePlus Genetics, n.d.)

These include tests that examine:

• one known DNA variant

• one specific gene

• several selected genes

• the protein-coding portion of the genome

• most of the genome

• chromosomes or larger sections of DNA

• gene activity or gene-related proteins and enzymes

We can also describe genetic tests according to their use, including screening, diagnostic, carrier, predictive, prenatal, newborn, pharmacogenetic, forensic, and relationship testing.

These two classifications overlap. A gene panel, for example, describes what is analyzed. Carrier screening describes why testing is being performed.

Types of Genetic Testing by What They Analyze

The biggest difference between many gene tests is scope. Some ask a narrow question; others examine a much larger amount of genetic material.

Targeted Variant and Single-Gene Testing

A targeted variant test looks for one specific genetic change that has already been identified as relevant to the testing question. Its scope is narrow.

Single gene testing goes a step further. Instead of checking only one predetermined change, the laboratory examines one specific gene for relevant variants or gene changes.

A targeted test asks, in effect, whether a particular DNA change is present. A single-gene test asks a broader question about the selected gene.

Fenix's focused APOE and MTHFR tests provide examples of targeted genetic testing. The APOE report identifies a person's ε2, ε3, and ε4 allele status, while the MTHFR report examines common variants including C677T and A1298C. These focused tests answer narrower questions than whole-exome or whole-genome sequencing. 

Gene Panel Testing

A gene panel examines a selected group of genes at the same time. This can be useful when several genes could relate to the same clinical or biological question and more than one gene may be relevant. A genetic testing panel brings the relevant genes together in one test so you don't have to have each gene analyzed separately.

There's no universal panel size. One panel may include a small group of genes, while another may offer a much larger panel for a similar purpose. That makes the list of genes included in the test important when comparing panel testing options involving one or more genes.

Whole Exome and Whole Genome Sequencing

Whole exome sequencing focuses mainly on exons, which are the protein-coding sections of genes. Although these coding regions represent only part of the genome, they contain many variants that researchers and clinicians already know how to interpret.

Whole genome sequencing takes a broader approach and examines much more of the genetic code, including coding and noncoding regions. These broader approaches may also be described as genomic testing.

That doesn't mean whole genome sequencing is automatically the better choice. Broader testing can reveal far more genetic variation, but not every finding has a clear or useful interpretation. The best scope depends on the purpose of testing rather than simply how much DNA can be examined. (MedlinePlus Genetics, n.d.)

Chromosome, Gene Expression, and Biochemical Tests

Not every genetic test involves reading DNA one letter at a time. Chromosome testing looks for larger changes involving chromosomes or substantial sections of genetic material. A chromosomal microarray, for example, can identify certain losses or gains of chromosomal material, including some missing or extra pieces of DNA. (GeneReviews, n.d.)

Gene expression tests examine which genes are active and how strongly they're expressed. Biochemical testing takes a different route, measuring the quantity or activity of particular proteins or enzymes that are produced through genetic instructions. Other tests therefore answer questions about genetic function rather than DNA sequence itself.

These methods answer different questions, which is another reason genetic testing can't be framed as one single laboratory procedure.

Genetic Tests Can Also Be Grouped by Their Purpose

The second classification system concerns why testing is being performed.

Diagnostic and Screening Tests

Genetic screening and diagnostic testing are related, but they aren't interchangeable. Screening generally looks for indications of whether additional evaluation could be useful. It doesn't necessarily provide a final answer.

Diagnostic testing is used when there is already a more specific clinical question. Importantly, “screening” and “diagnostic” describe the purpose of testing rather than one particular laboratory technology. (MedlinePlus Genetics, n.d.)

Carrier, Prenatal, and Newborn Testing

• Carrier screening looks for inherited genetic changes that a person could potentially pass to a child.

• Prenatal genetic testing can be done during pregnancy. It may include screening or more targeted diagnostic approaches, depending on the reason for testing.

• Newborn screening tests is a broader public-health program performed soon after birth. Many newborn screening tests look for inherited or metabolic conditions, sometimes through biochemical testing rather than direct DNA analysis. are performed soon after birth and checks for selected inherited or metabolic findings for which early identification may be useful.

Predictive and Pharmacogenetic Testing

Predictive or presymptomatic testing looks for genetic variants associated with potential future health outcomes before related signs are present.

Pharmacogenetic testing examines genetic differences that may influence how a person processes or responds to certain medicines. It doesn't apply to every medicine, and the usefulness of the information depends on the specific gene-medicine relationship being assessed.

Forensic and Relationship Testing

Genetic testing also has applications outside healthcare. DNA can help establish biological relationships or support identification in forensic settings.

These tests rely on genetic information, but their purpose is very different from health-focused genetic testing.

Clinical Genetic Testing vs. At-Home Genetic Testing

The phrase “direct-to-consumer genetic testing” (DTC gene testing), also known as direct-to-consumer (DTC) testing, describes how a test is accessed, and not the type of genetic technology used.

In clinical genetic testing, a healthcare professional is involved in selecting, ordering, or interpreting a test within a clinical context. A healthcare provider may consider medical history, personal or family history, previous results, and the specific testing question when choosing a test. The choice of test can take medical history, family history, previous results, and the specific testing question into account.

At-home testing provides a different access route. Depending on the company and product, a consumer may collect a saliva or cheek-swab sample at home and receive a report without following the same clinical pathway.

The FDA notes that direct-to-consumer tests differ in the genetic variants they assess and in the amount of evidence supporting the information provided. That makes the scope and intended use of the individual test more informative than the label “at-home” by itself. (U.S. Food and Drug Administration, n.d.)

Fenix Health Science offers focused at-home genetic test kits using cheek-swab collection. The reports are intended to provide genetic information and are not a substitute for clinical genetic testing or a clinical genetic consultation.

One option, the APOE4 gene test, provides a focused report identifying APOE genotype, including ε2, ε3, and ε4 status.

The MTHFR gene test reports common MTHFR variants, including C677T and A1298C, together with estimated MTHFR activity. Broader reporting options are also available. These reports are positioned for informational and educational use rather than as clinical genetic consultations.

What Genetic Test Results Can and Cannot Tell Someone

Genetic test results are interpreted according to what the test was designed to examine.

Positive, Negative, and Uncertain Results

A positive result generally means that the laboratory identified the genetic finding being assessed. What that finding means depends on the test, the variant, and the reason for performing the test.

A negative result means the test didn't identify the finding or findings within its scope. It doesn't rule out every possible genetic contribution. Some tests examine selected variants, and current scientific knowledge doesn't provide a complete interpretation of every change in human DNA.

A variant of uncertain significance, often shortened to VUS, is a genetic change for which the available evidence doesn't yet establish a clear clinical meaning. (MedlinePlus Genetics, n.d.)

Unexpected or Secondary Findings

Broader testing can uncover genetic information unrelated to the original reason the test was ordered. These are often called secondary or incidental findings.

That possibility illustrates an important limitation of the idea that more testing is always better. A larger amount of genetic data can also create more information that requires careful interpretation.

How Is the Right Genetic Test Chosen?

The most useful genetic test is usually the one that matches the question. A known family variant may lead to consideration of targeted testing, particularly when the variant has already been identified in other family members. If one particular gene is strongly relevant, single-gene testing may provide an appropriately focused approach. When multiple genes could explain the same finding, panel testing can examine those possibilities together.

Broader exome or genome testing may be considered when narrower testing hasn't provided useful information or when the genetic question is particularly complex. If the suspected change is chromosome-scale, a chromosome-focused method may be more appropriate.

For clinical questions, personal history, family history, previous results, and the limits of each testing method are all important. Genetic counseling can help with test selection before testing and with understanding results afterward. (Centers for Disease Control and Prevention, 2024.)

Conclusion

There's no single definitive list of genetic tests because the terminology describes two different things: what a test examines and why it is being used.

By scope, testing can move from a targeted DNA variant to a specific gene, a genetic testing panel, an exome, or almost the entire genome. Other approaches look at chromosomes, gene activity, proteins, or enzymes. By purpose, the same field includes screening, diagnostic, carrier, predictive, prenatal, newborn, and pharmacogenetic testing.

The widest test isn’t automatically the most useful. The right scope depends on the question being asked, the information already available, and how the results will be used. Readers interested in focused, informational testing can also explore our at-home genetic testing options alongside the wider clinical testing landscape.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

References

Centers for Disease Control and Prevention. (2024). Genetic testing.

GeneReviews. (n.d.). Genetic testing: Current approaches. National Center for Biotechnology Information.

MedlinePlus Genetics. (n.d.). How are genetic screening tests different from genetic diagnostic tests?

MedlinePlus Genetics. (n.d.). What are the different types of genetic tests?

MedlinePlus Genetics. (n.d.). What are the uses of genetic testing?

MedlinePlus Genetics. (n.d.). What do the results of genetic tests mean?

U.S. Food and Drug Administration. (n.d.). Direct-to-consumer tests.