The difference between different types of genetic tests and how to choose the most suitable one for you
With the continuous advancements in genetic medicine, it has become possible to study DNA and identify genetic variations that may be linked to many health conditions. Given the multitude of genetic tests available, some may be confused about the difference between single-gene analysis, gene panel analysis, and whole-exome analysis.
Choosing the right test depends not only on the number of genes covered by the test but also on symptoms, medical and family history, the purpose of the analysis, and how well each test can answer the medical question at hand.
Hence the importance of understanding the differences between various genetic tests before making a decision, in collaboration with a doctor or genetic consultant.
What is meant by genetic testing?
Genetic testing involves examining genetic material (DNA) to detect changes that may help diagnose certain genetic diseases, understand their causes, or assess associated risks.
These tests differ in the scope of analysis, the method of selecting the genes to be studied, and the type of changes that can be detected.
Some tests focus on a single gene known to be associated with a specific condition, while others include a group of genes associated with similar symptoms. The study may extend to large portions of the genetic material if the likely cause of the condition is unclear.
Enigma Genomics helps raise awareness of the importance of genomic medicine and the role of genetic testing in supporting medical assessment and understanding genetic variations that may be associated with different health conditions.
First, analyze one gene.
Single gene testing is a test that focuses on a specific gene when symptoms or medical information suggest the possibility of genetic variations associated with that gene.
This option is appropriate in some cases where the likely genetic cause is well known or when a specific familial mutation has been previously detected in a family member.
When is single-gene analysis appropriate?
The doctor may recommend this type of test in the following cases
The presence of symptoms that are highly consistent with a genetic disorder linked to a specific gene.
The presence of a known genetic variant within the family
The need to check for a specific genetic change in a relative
Monitoring a known genetic condition requires targeted genetic testing.
What are the advantages of single-gene analysis?
This test helps to focus on the most likely genetic cause instead of studying a large number of genes without a clear medical need.
The result may be easier to interpret when the relationship between the gene and the health condition is well known.
However, there are some limitations to be aware of. If the symptoms are caused by another gene, a single-gene test will not be able to detect this cause unless it is appropriately included in the test.
Therefore, the choice of test should be based on a thorough clinical assessment and not merely on the desire to conduct a limited analysis.
Secondly, the Gene Panel
A genetic panel is a test that includes a group of genes that are associated with a specific disease or a group of similar symptoms.
Instead of analyzing just one gene, several genes can be studied simultaneously, which may help in reaching a diagnosis when there are multiple potential genetic causes for the condition.
When is a genetic panel the right option?
Genetic paneling may be helpful when symptoms suggest a genetic disorder with more than one possible genetic cause.
Examples include some cases of hereditary hearing loss, retinal disorders, some hereditary heart diseases, and metabolic disorders.
It may also be used in the evaluation of certain hereditary cancers when the goal is to study a group of genes associated with a high probability of developing the disease.
What are the characteristics of a genetic blueprint?
The panel allows for the study of multiple genes associated with the same condition during a single test, rather than conducting separate tests for each gene.
The chances of reaching a genetic diagnosis may increase when symptoms are consistent with a known set of genes.
However, the scope of the panel varies from test to test; not all panels are the same in the number of genes or types of changes that can be detected.
A negative result does not rule out all possible genetic causes; the responsible gene may not be included in the panel, or the test may fail to detect a particular type of mutation.
Therefore, it is important to know which genes are covered by the test and its technical limitations before conducting the analysis.
Third, Whole Exome Sequencing
Whole-exome analysis is a genetic test that studies exons, which are the segments of DNA that carry the instructions for making proteins.
These parts represent a small percentage of the human genome, but they contain many variations known to be associated with genetic diseases.
Exome analysis is used in some cases where the genetic cause is not clear or when symptoms are complex and may be related to more than one gene.
When might a doctor recommend an exome analysis?
This test may be a suitable option in some of the following cases.
Having multiple symptoms affecting more than one system in the body
Suspected genetic disease without knowing the responsible gene
Failure to reach a diagnosis after previous genetic testing
The presence of a complex condition necessitates the study of a large number of potential genes.
The analysis may be performed on the individual alone or, in some cases known as triple exome analysis, on both parents. This can help in understanding how genetic changes are passed on and determining their correlation with symptoms.
What are the advantages of exome analysis?
Exome analysis allows for the study of a large number of genes in a single test and may help in reaching a diagnosis when there is no clear hypothesis about the responsible gene.
However, exome analysis does not study all parts of the genome and does not necessarily detect all types of genetic changes.
Some changes may occur outside the exons or require other techniques to detect, and results may appear with uncertain significance that require further evaluation.
Therefore, the results should be interpreted in collaboration with specialists and based on symptoms, medical history, and family history.
What is the difference between single-gene analysis, gene panel analysis, and exome analysis?
The fundamental differences between these tests can be understood through the scope of the analysis and the purpose for which it is performed.
single-gene analysis
It focuses on a specific gene and is appropriate when there is a known potential genetic cause or a specific familial genetic variant.
genetic blueprint
It includes a set of genes associated with a particular condition or symptom and is useful when there are several potential genetic causes within the same range.
Whole exome analysis
It studies the protein-coding regions in a large number of genes and is used in some complex cases where it is difficult to identify the gene responsible beforehand.
This does not mean that broader testing is always best; analyzing a single gene may be more appropriate when the cause is known, while a genetic panel or exome analysis may be more suitable when there are multiple possibilities.
How to choose the right genetic test
The right choice begins with identifying the medical question we need to answer.
If a family member has a known mutation, it may be appropriate to begin with targeted testing for that mutation. However, if the symptoms are consistent with a range of genetic diseases, genetic panel analysis may be more suitable.
In cases where symptoms are multiple and the cause is unclear, the doctor may discuss the possibility of performing an exome analysis or other tests, depending on the case.
There are several factors that help determine the appropriate test.
Symptoms and medical history
The doctor needs to know the nature of the symptoms, when they appeared, how they progressed, and whether they affect one or more body systems.
Family history
Having similar cases within a family may help identify inheritance patterns and genes worthy of further investigation.
Types of changes the scan looks for
The ability of tests to detect mutations, small or large changes, and some structural alterations varies; therefore, a technique appropriate to the medical suspicion should be chosen.
Genetic counseling
Genetic counseling helps clarify the goals and limitations of testing, the potential outcomes, and what they might mean for the individual and their family members.
What do the results of genetic testing mean?
The result of a genetic test can be positive, negative, or inconclusive depending on the type of test and the findings.
Positive result
It may indicate the discovery of a genetic alteration known or likely associated with the condition being evaluated, and the impact of the result depends on the nature of the alteration and the medical context.
Negative result
This means that the test did not detect a change that explains the condition within the limitations of the technique used and the genes included in the examination, but it does not rule out all possible genetic causes.
The change is of uncertain significance
The analysis may reveal a genetic change for which there is insufficient evidence to clearly establish its relationship to the disease, and it should not be treated as a definitive cause of the condition or used as the basis for major medical decisions.
All results require expert interpretation that takes into account symptoms, family history, and the limitations of the test.
Is exome analysis better than genetic panel analysis?
There is no single answer that fits all cases because the choice depends on the purpose of the examination.
Genetic panel analysis may be more appropriate when symptoms are clear and linked to a specific set of genes, while exome analysis may be useful when symptoms are complex or there is no specific genetic cause to begin with.
The ability of each test to detect the required types of changes and the availability of an appropriate medical interpretation of the results must also be considered.
In some cases, the evaluation may begin with a genetic panel, and the doctor may then move on to a broader analysis if a diagnosis is not reached.
Enigma Genomics' role in spreading genetic awareness
Understanding the different types of genetic testing helps in making more informed decisions when discussing available options with a doctor.
Enigma Genomics emphasizes the importance of choosing a test based on medical need, not just on the number of genes covered by the test.
Each test has a specific scope, features, and limitations, and reaching a useful result depends on choosing the appropriate test, analyzing the data, and interpreting it within the context of the health condition.
If you are looking for information about genetic testing or want to understand the differences between types of tests, it is important to discuss your case with a specialist to determine the most appropriate option.
Single-gene analysis differs from gene panel and exome analysis in terms of the scope of the study and the purpose of the examination.
Single-gene analysis focuses on a specific genetic cause, while a gene panel includes a set of genes associated with a particular condition. Exome analysis studies the protein-coding regions of a large number of genes and may be useful in complex cases.
Choosing the best test depends not only on its scope but also on the symptoms, family history, and the medical question that needs answering.
Understanding these differences is an important step towards using genetic testing appropriately and obtaining information that can be used in medical evaluation and health decision-making.