Genetic Testing
What Is Genetic Testing?
Genetic testing is a medical test that looks for changes, known as genetic variants, in a person’s DNA, chromosomes or, in some cases, proteins. Some genetic variants can cause or contribute to health conditions, while others may have little or no known effect.
Genetic testing can be used for different medical reasons. It may help identify the cause of symptoms, confirm or rule out a suspected inherited condition, assess the risk of developing certain conditions, or determine whether a genetic variant may be passed on to children. The type of genetic test used depends on the medical question, personal and family history, and the condition being investigated.
Genetic tests can examine a specific genetic variant, one or more genes, chromosomes, or much larger portions of DNA such as the exome or genome. No single genetic test can identify every genetic condition, so choosing the appropriate test is an important part of the clinical process.
For clinical genetic testing, results are interpreted alongside relevant medical and family history. This helps explain what a result may mean for the individual and, in some circumstances, their relatives. A genetic test can provide useful information, but it does not always provide a definitive answer about a person’s future health.
What Can Genetic Testing Help Identify?
Genetic testing can help identify genetic changes associated with a wide range of health conditions. Depending on the type of test and the reason for testing, it may help explain unexplained symptoms, confirm a suspected inherited condition, or identify a genetic change that may affect a person’s health or their family.
Genetic testing may be considered when there is:
A suspected inherited condition — testing may help identify a genetic cause for symptoms or a condition that runs in a family.
A significant family history — testing can help determine whether a known or suspected genetic change has been inherited.
An increased risk of hereditary cancer — testing may identify inherited genetic variants associated with an increased risk of certain cancers.
Unexplained medical or developmental symptoms — genetic testing may help investigate conditions where a genetic cause is suspected.
Pregnancy or reproductive concerns — certain tests can assess the likelihood of particular genetic or chromosomal conditions or whether a person carries a variant that could be passed to a child.
A previously identified genetic variant in the family — testing may determine whether other family members carry the same variant.
Genetic testing does not always provide a definitive diagnosis or predict whether someone will develop a particular condition. The usefulness of a test depends on the genetic condition being investigated, the person’s medical and family history, and the type of test performed.
If you are unsure whether your personal or family history may indicate a need for genetic testing, a Genetic Risk Assessment can help evaluate your individual circumstances and determine whether genetic testing may be appropriate.
Types of Genetic Testing
Genetic testing can be used for different clinical purposes, depending on a person's symptoms, medical and family history, and the question that needs to be investigated. Different tests are designed to look for different types of genetic information, from a specific genetic variant to changes across many genes or the wider genome.
The most appropriate approach depends on what needs to be investigated. Genetic testing may be used to investigate a suspected condition, assess inherited risk, identify carrier status, investigate genetic factors associated with cancer, or examine genetic changes acquired by tumour cells.
Genetic Testing by Clinical Purpose
Genetic testing is used in different clinical situations. The purpose of testing helps determine which type of analysis may be most appropriate.
Investigates a suspected genetic condition when symptoms, clinical findings or family history suggest that a genetic cause may be involved.
Looks for a known genetic variant to help assess the likelihood of developing a particular inherited condition, often before symptoms appear.
Determines whether a person carries a genetic variant that could potentially be passed on to their children.
Genetic and chromosomal testing during pregnancy can be used for screening or, in appropriate circumstances, to investigate a suspected condition.
Investigates inherited genetic variants that may be associated with an increased risk of certain cancers.
Examines genetic changes acquired by tumour cells during a person's lifetime rather than variants inherited from their parents.
Important: The purpose of testing and the clinical question being investigated help determine which genetic analysis is most appropriate. No single test can identify every genetic condition or genetic variant.
How Genetic Tests Differ in Scope
| Type of genetic analysis | What it examines |
|---|---|
| Targeted variant testing | Looks for a specific genetic variant that is already known to be relevant to the individual or family. |
| Single-gene testing | Examines one gene when the clinical features strongly suggest a condition associated with that gene. |
| Multi-gene panel testing | Analyses a group of genes associated with a particular condition or group of related conditions. |
| Chromosomal testing | Examines chromosomes to identify changes in chromosome number or structure. |
| Whole exome sequencing | Analyses the protein-coding regions of many genes and may be considered when a wider genetic investigation is needed. |
| Whole genome sequencing | Analyses a person's genome more broadly and can identify genetic changes across both coding and non-coding regions. |
The most appropriate test depends on the clinical question and the individual's circumstances. Where there is a significant personal or family history, a Genetic Risk Assessment may help determine whether genetic testing could be appropriate and what type of investigation may be relevant.
For more information about specific clinical testing services, explore our Inherited Disorders Testing, Prenatal Genetic Testing, Cancer Genetic Testing, Somatic Genomic Testing and Genetic Test Re-analysis pages.
Who May Benefit From Genetic Testing?
Genetic testing may be considered when a person’s symptoms, medical history or family history suggest that genetic factors could be relevant to their health. It can also be useful when a known genetic condition or variant has already been identified within a family.
Testing may be worth considering for people who have:
- A family history of an inherited condition or a known genetic variant in a close relative.
- Unexplained symptoms or clinical findings that could have a genetic cause, particularly when routine investigations have not provided an explanation.
- A personal or family history of certain cancers that may suggest an inherited cancer predisposition.
- A known genetic condition in the family, where relatives may wish to understand whether they have inherited the same variant.
- Reproductive or pregnancy-related concerns, including a known inherited condition in either partner or a previous pregnancy affected by a genetic or chromosomal condition.
- A condition diagnosed at an unusually young age, or a pattern of related health problems affecting several members of the family.
- A previous genetic test with an inconclusive or uncertain result, where further review or updated analysis may be appropriate.
However, having a family history or a particular symptom does not automatically mean that testing is necessary. The value of genetic investigation depends on the individual circumstances, the pattern of disease in the family, and what information the result could provide.
How Does Genetic Testing Work?
The process usually begins by identifying the medical question that needs to be investigated. Your personal and family history, symptoms and other relevant clinical information help determine whether genetic testing may be appropriate and which type of analysis is most suitable.
Your medical and family history, symptoms and relevant clinical information are reviewed to understand what may be contributing to your health concerns and whether a genetic cause should be investigated.
The appropriate analysis depends on the clinical question. Testing may examine a specific variant, a single gene, multiple genes, chromosomes, the exome or a larger proportion of the genome.
Depending on the test, a biological sample such as blood, saliva, a cheek swab or, in some circumstances, tissue may be collected. The sample is then prepared for laboratory analysis.
Specialist laboratories analyse the relevant genetic material using appropriate molecular and genomic techniques. The analysis looks for genetic variants that may be relevant to the medical question being investigated.
Findings are interpreted in the context of the person's medical and family history. Not every genetic difference affects health, and some findings may require careful interpretation before their significance can be understood.
The results are explained in relation to the original clinical question. Depending on the findings, this may help inform further investigations, medical management, screening decisions or considerations for other family members.
Genetic testing is a clinical process, not simply a laboratory test. Choosing an appropriate analysis and interpreting the findings alongside the relevant medical and family history are important parts of understanding what the results may mean.
What Are the Limitations of Genetic Testing?
Genetic testing can provide valuable information, but it cannot answer every health question or predict a person’s future with certainty. The usefulness of a result depends on the condition being investigated, the type of analysis performed and how the findings are interpreted in the context of the individual’s medical and family history.
Some important limitations include:
- Not every condition has a known genetic cause. Many health conditions result from a combination of genetic, environmental and lifestyle factors, so a genetic test may not identify a clear explanation.
- A negative result does not always rule out a condition. A test may not detect every possible genetic change, and some variants may not yet be known or detectable using the method performed.
- Some findings have uncertain significance. A genetic test may identify a variant whose effect on health is not currently understood. Such a result does not necessarily mean that the variant causes disease.
- Results may indicate increased risk rather than certainty. For some inherited conditions, identifying a relevant variant may show an increased likelihood of developing a condition rather than confirming that it will definitely occur.
- Genetic information can have implications for relatives. A finding may be relevant to other family members because genetic variants can sometimes be shared between relatives.
- Scientific knowledge continues to change. New research can alter how previously identified genetic variants are understood. In some circumstances, previously generated genetic data may therefore benefit from future review or re-analysis.
For these reasons, genetic results should be interpreted carefully rather than viewed in isolation. A result is most useful when considered alongside the person’s clinical history, family history and the specific question that led to testing.
Understanding Genetic Test Results
Receiving a genetic test result does not always mean receiving a simple yes-or-no answer. The meaning of a finding depends on the type of test performed, the genetic variant identified, and how the result fits with your medical and family history.
Results are generally interpreted according to the evidence available about a particular genetic variant. Some findings may clearly indicate a genetic cause, while others may provide useful information about risk or require further investigation. In some cases, no relevant genetic change is identified.
Understanding the different types of results can help put a genetic report into context.
| Result | What It May Mean | What Happens Next |
|---|---|---|
| Pathogenic or likely pathogenic variant | A genetic variant has been identified with sufficient evidence to indicate that it may contribute to a particular genetic condition or increased disease risk. | The finding is considered alongside the clinical and family history to determine its relevance and any appropriate medical or family implications. |
| Variant of uncertain significance | A genetic difference has been identified, but there is currently insufficient evidence to determine whether it affects health. | The finding should not usually be treated as evidence that a person has or will develop a genetic condition. Its interpretation may change as scientific knowledge develops. |
| Negative result | No relevant genetic change was identified by the test that was performed. | A negative result does not necessarily exclude a genetic cause. Its significance depends on the condition investigated, the test's scope and the individual's clinical history. |
| Inconclusive result | The analysis may not provide enough information to establish a clear genetic explanation for the clinical question. | Depending on the circumstances, further clinical assessment, additional testing or review of existing genetic data may be considered. |
A result should therefore be interpreted in context rather than in isolation. The same genetic finding can have different implications depending on the person's symptoms, family history and the reason the analysis was performed.
Genetic information can also become more informative over time as new evidence emerges. For people with older, negative or inconclusive results, updated scientific knowledge may sometimes provide an opportunity to reassess previously generated data.
Genetic Testing for Different Clinical Conditions
The appropriate genetic investigation depends on the health question being considered. Different clinical circumstances require different approaches, ranging from investigating an inherited condition to assessing genetic factors associated with pregnancy or cancer.
Inherited Disorders
Genetic investigation may be considered when symptoms, a diagnosis or family history suggest that an inherited condition could be involved. This can include rare genetic disorders as well as conditions caused by variants affecting specific genes or groups of genes.
Prenatal Genetic Testing
During pregnancy, genetic and chromosomal testing can be used for different purposes, including screening for certain conditions or investigating a specific concern identified during pregnancy. The appropriate approach depends on factors such as gestational age, previous results and individual circumstances.
Cancer Genetic Testing
Some cancers can be associated with inherited genetic variants that increase susceptibility to certain types of cancer. Identifying an inherited predisposition may provide information relevant to screening, risk management and, where appropriate, other family members.
Somatic Genomic Testing
Somatic genomic testing focuses on genetic changes acquired by tumour cells during a person’s lifetime rather than variants inherited from their parents. These findings can provide information that may be relevant to understanding a tumour and, in some circumstances, treatment decisions.
The choice of investigation should be based on the specific clinical question rather than simply the availability of a particular test. This helps ensure that the information generated is relevant and can be interpreted appropriately within the wider clinical context.
Specialised Genetic Testing
Not all genetic services are focused on diagnosing inherited conditions or assessing disease risk. Some specialised approaches explore how genetic differences may relate to areas such as nutrition and physical performance. These services are best viewed as an additional source of information rather than a replacement for established medical assessment or personalised professional advice.
Nutrigenomics
Nutrigenomics explores relationships between genetic variation and the way the body may respond to certain nutrients or dietary factors. Depending on the analysis, the findings may provide information that can be considered alongside an individual’s nutritional habits, lifestyle and wider health profile.
Learn more about our Nutrigenomics Genetics Testing service.
Sports Genetics
Sports genetics examines selected genetic variations that have been studied in relation to areas such as exercise response, muscle characteristics, recovery and other aspects of physical performance. These findings should be interpreted carefully, as athletic performance is influenced by many genetic, environmental, training and lifestyle factors.
Learn more about our Sports Genetics Testing service.
These specialised analyses are most useful when their limitations and the current strength of scientific evidence are taken into account, rather than treating genetic findings as definitive predictions of an individual’s nutritional needs or athletic potential.
Genetic Testing and Genetic Counselling
Genetic testing and genetic counselling are closely connected, but they serve different purposes. Genetic testing provides information about a person’s genes, chromosomes or other genetic material, while genetic counselling helps explain why testing may be appropriate and what the results could mean.
Genetic counselling may take place before testing to review your personal and family history, discuss the potential benefits and limitations of testing, and help determine which approach may be most appropriate. After testing, counselling can also help explain the result and consider what it may mean for your health and, where relevant, for family members.
Genetic counselling can be particularly helpful when genetic testing may have important medical or family implications. It provides an opportunity to discuss the possible outcomes of testing before making a decision and to understand the result within the context of your individual circumstances.
Genetic Counselling
If you are considering genetic testing and would like to understand whether testing is appropriate, what it may involve, or how the results could affect you and your family, Genetic Counselling can provide personalised guidance throughout the process.
Why Choose London Genetics for Genetic Testing?
Choosing a genetic testing provider involves more than selecting a laboratory test. The quality of the testing process, the relevance of the analysis, and appropriate interpretation of the results all contribute to obtaining useful and meaningful genetic information.
What to Consider When Choosing a Genetic Testing Service
Clinical Relevance: The genetic test should be appropriate for the medical question being investigated and take relevant personal and family history into account.
Laboratory Quality: Genetic testing should be carried out using appropriate laboratory methods and quality standards for the type of analysis being performed.
Expert Interpretation: Genetic results can be complex. Appropriate clinical expertise can help explain what a result means, its limitations, and whether further assessment or follow-up may be appropriate.
Why London Genetics?
At London Genetics, we take a personalised approach to genetic testing, considering the reason for testing alongside relevant medical and family history. This helps ensure that the testing process is focused on the clinical question rather than simply producing genetic data.
We also recognise that a laboratory report is only one part of the genetic testing process. Results need to be interpreted in their clinical context, including their potential significance, limitations, and relevance to family members.
Our approach is designed to help patients understand their genetic information clearly and make informed decisions about appropriate next steps.
If you are considering genetic testing and would like to discuss whether it may be appropriate for your circumstances, arrange a consultation with London Genetics to explore your options.
Book a Consultation
Dr Ehsan Karimiani
Frequently asked questions
In this section you can check frequently asked questions.
What is genetic testing?
Genetic testing is a medical test that examines a person’s DNA, chromosomes or, in some cases, proteins to identify genetic variants that may be relevant to their health. The type of testing performed depends on the medical question being investigated.
What can genetic testing tell me?
Genetic testing may help identify a genetic cause for certain symptoms, confirm a suspected genetic condition, assess the likelihood of developing particular conditions, or determine whether a genetic variant may be relevant to family members. The information provided depends on the type of test and the condition being investigated.
Who should consider genetic testing?
Genetic testing may be considered when a person’s symptoms, diagnosis, personal history or family history suggest that a genetic factor could be relevant. It may also be appropriate in certain reproductive or risk-assessment situations. Whether testing is useful depends on the individual’s circumstances and the clinical question.
Does genetic testing always provide a clear answer?
No. Genetic testing does not always identify a genetic explanation. A result may be negative, inconclusive, or identify a genetic variant whose significance is not currently known. A negative result also does not necessarily rule out a condition, as some genetic changes may not be detectable by the particular test performed.
How is a genetic test performed?
Most genetic tests require a biological sample, such as blood, saliva or another suitable sample depending on the test. The sample is analysed in a laboratory using methods appropriate to the genetic question being investigated. The findings are then interpreted in the context of relevant clinical information.
How long does it take to receive genetic test results?
The time required varies depending on the type and complexity of the genetic analysis, the laboratory process and the reason for testing. Some tests may produce results relatively quickly, while more complex analyses can take longer.
What does a positive genetic test result mean?
A positive result can have different meanings depending on the genetic variant identified and the reason for testing. In some circumstances, it may confirm a genetic diagnosis or indicate an increased risk of a particular condition. A positive result should therefore be interpreted in the context of the individual’s clinical and family history.
What is a variant of uncertain significance?
A variant of uncertain significance, or VUS, is a genetic change for which there is currently insufficient evidence to determine whether it affects health. A VUS should not normally be treated in the same way as a clearly disease-causing variant, and its interpretation may change as scientific knowledge develops.
Can genetic testing affect my family?
Potentially. Genetic findings may sometimes be relevant to biological relatives because family members can share genetic variants. Depending on the result and the condition being investigated, genetic information may therefore have implications beyond the person who was tested.
Can genetic test results change over time?
The underlying genetic data do not normally change, but our understanding of a genetic finding can change as scientific evidence develops. A variant that was previously difficult to interpret may become better understood as new research and clinical information become available.
Is genetic counselling necessary before genetic testing?
Not every genetic test requires genetic counselling, but counselling can be valuable when testing has potentially significant medical, reproductive or family implications. It can help explain the purpose and limitations of testing and support informed decision-making before and after testing.
Is genetic testing suitable for everyone?
No. Genetic testing is not automatically appropriate for every person or every health concern. The value of testing depends on the medical question, the available evidence, personal and family history, and whether the result could provide useful information for the individual.
I’m thinking about getting a genetic test for health insights, but I’m not entirely sure how accurate these reports are. Could someone tell me how detailed the results from London Genetics actually are?
Hi Emily, thanks for your question. Our health-focused genetic panels are designed to be highly comprehensive, using clinically validated markers. While the reports don’t provide a medical diagnosis, they do offer clear, evidence-based insights into potential risks and personalised lifestyle guidance. If you choose to proceed, I’d be happy to walk you through your results in detail.
How long does it usually take to receive the results? I’m travelling soon and hoping the process isn’t too slow.
Hi Oliver. Our standard turnaround time is between two and three weeks from the moment the sample reaches our lab. If you’re travelling, we can note your dates and keep you updated so you won’t miss your report. Just let us know if you need any adjustments to the schedule.
Just received my genetic report — genuinely impressed with how clear and well-structured it is. A very polished service.
Thank you, Rebecca. We’re glad to hear you found the report clear and helpful. If you’d like to schedule your complimentary follow-up consultation, feel free to contact the clinic anytime.
Is the testing suitable for children as well, or is it mostly designed for adults?
Hi Charlotte. Some of our non-medical tests—such as ancestry and general wellness—are suitable for children. However, for health-related genetic testing, we strongly recommend a discussion with a GP or paediatric specialist first to ensure it’s appropriate. If you’d like guidance, our team can help you evaluate the options.
I have a family history of heart disease and I’m wondering whether genetic testing can actually help with prevention, or if it’s more for information only?
Hi Daniel. That’s a very important question. Genetic testing can be extremely helpful for prevention, especially when there is a known family history. While it doesn’t predict certainty, it highlights inherited risk factors that allow for earlier monitoring, lifestyle adjustments, and preventive strategies in collaboration with your GP or cardiologist.
Is the DNA sample collection done at home, or do I need to visit the clinic in person?
Hi Sophie. We offer both options for convenience. Many of our tests can be completed using an at-home collection kit with clear instructions. For certain specialised tests, a clinic visit may be recommended. Our team will guide you on the most suitable option based on the test you choose.
Yes, they do. I booked a follow-up call with one of their specialists, and it made a huge difference. They explained everything in plain English.
Some of the tests are fine for kids, especially the ancestry and general wellness ones. But anything health-related for minors is best discussed with a GP first.
Mine arrived in just under three weeks. They kept me updated throughout, so you shouldn’t be left wondering. Quite efficient, really.
Hi Emily, thanks for your question. Our health-focused genetic panels are designed to be highly comprehensive, using clinically validated markers. While the reports don’t provide a medical diagnosis, they do offer clear, evidence-based insights into potential risks and personalised lifestyle guidance. If you choose to proceed, I’d be happy to walk you through your results in detail.
Hi Oliver. Our standard turnaround time is between two and three weeks from the moment the sample reaches our lab. If you’re travelling, we can note your dates and keep you updated so you won’t miss your report. Just let us know if you need any adjustments to the schedule.
Hi Charlotte. Some of our non-medical tests—such as ancestry and general wellness—are suitable for children. However, for health-related genetic testing, we strongly recommend a discussion with a GP or paediatric specialist first to ensure it’s appropriate. If you’d like guidance, our team can help you evaluate the options.
Hi Hannah. Yes, absolutely. Every health report includes the option for a follow-up consultation with one of our clinicians. During the call, we review your results line by line, answer any questions, and help you understand how to apply the findings to your lifestyle or future healthcare decisions.
Thank you, Rebecca. We’re glad to hear you found the report clear and helpful. If you’d like to schedule your complimentary follow-up consultation, feel free to contact the clinic anytime.
Do you provide any follow-up consultation to explain the results? I’d prefer not to interpret everything on my own.
Hi Hannah. Yes, absolutely. Every health report includes the option for a follow-up consultation with one of our clinicians. During the call, we review your results line by line, answer any questions, and help you understand how to apply the findings to your lifestyle or future healthcare decisions.