Genetic Testing

Genetic Testing

If you or your child are exhibiting symptoms that don’t immediately offer an immediate diagnosis, or if a family member already has a genetic condition, doctors might investigate the possible inheritance of a genetic condition or the spontanous appearance of a gene mutation. They will probably suggest genetic testing.

What is a genetic test?

A genetic test looks at one or more genes; these make up part of our genetic code.  Genes are the instructions we all carry, which we inherit from our parents.  They are made of DNA and are stored on chromosomes.  They help to make our bodies grow and work well most of the time.  If part of the genetic code is changed, rearranged or missing it can affect growth, development or health.  Some illness is caused by a genetic change.

What is a genomic test?

A genomic test looks at a person’s genome.  A genome is all of the genetic code of that person, not just one gene or chromosome.  Whole Genome Sequencing (WGS) creates lots of data but not all of it can lead to results that are useful at the moment.  The 100,000 genome project helped make some links between changes in genomes and health issues.  Genomic testing may become a regular part of healthcare in the future and is already being offered by the NHS in some situations.  More research in this area is planned:

Why are genetic tests carried out?

Genetic tests look for changes in the genetic code that could explain or predict symptoms of illness or disease.  There are many different types of test, which are described below. 

Where can I get a genetic test?

Most genetic testing relating to health is carried out in hospitals, often in NHS Genetics Clinics or Genomic Centres. If you are eligible for NHS care please ask your GP if you think you would benefit from genetic testing. They should know the criteria for a referral and will make the arrangements if suitable. If you are pregnant and think you or your baby may require a genetic test which is different from the usual screening in pregnancy, then please contact your GP. midwife or local genetics clinic as soon as possible. Some genetic tests relating to pregnancy are best carried out as early in pregnancy as possible. 

Private testing is available in some situations.  Please read our section about this below.

Direct to consumer genetic tests allow people to send off their own samples and receive results without going through a health professional.  For more information about this read below.

Types of Genetic Test

There are different types of genetic test and different reasons for carrying them out.

Diagnostic test – this test is done to try to find or confirm a suspected diagnosis.  It is usually carried out on someone who has symptoms or features of a disease or illness. 

Carrier test – this test is usually carried out on someone who is well (healthy) but may be a carrier of a recessive or X linked genetic condition.  Depending on the results they could potentially have children who are affected with the condition.  Certain recessive conditions are more likely depending on our ethnic background.

Presymptomatic or predictive test – this test looks at future health risks, usually in someone who knows there is a chance they have inherited a genetic condition which develops over time. 

Prenatal test (invasive or non invasive) – this test looks at the genetic code of a baby in the womb.  An invasive test could test either the amniotic fluid or a small sample from the placenta.  A non invasive test examines tiny traces of fetal DNA that is freely floating in the mother’s bloodstream.

Preimplantation genetic testing or diagnosis (PGT or PGD) – this test is carried out on embryos created by IVF with the aim of reducing the chance of genetic disease.  These tests can look at single genetic conditions (PGT-M), chromosome structure (PGT-SR), or chromosome numbers (PGT-A).

Pharmacogenetic or pharmacogenomic testing – tests to help work out what medication type or dose is most likely to be helpful, or to predict side effects, based on genetic code.  There are hopes that there will be more tests like this available in the future.

Screening tests during pregnancy – these tests can show the chance of a genetic condition affecting a baby or may lead to more tests being offered to help clarify the risk.  There are detailed information leaflets about the options available. with an embedded animation explaining screening options

Newborn spot test – this can identify some genetic conditions.  Follow up testing may be needed.  More details can be found here

Forensic test – can help to identify those connected with a crime scene.  Genetic testing can be carried out many different kinds of sample including blood, saliva, teeth, semen and faeces. 

Paternity/maternity test – identification of the biological father/mother by genetic testing.

How long does a genetic test take?

Genetic testing can be quick or take a long time.  This depends on the kind of testing being done and if other samples are also needed (e.g. if other family members need to also give a sample).  Please ask for details when you are giving your sample (usually blood, occasionally saliva) for testing.

What is consent?

Most genetic tests require that permission is given first – ‘consent’. This involves a discussion and a form may be signed to indicate your agreement and understanding. There are issues which can be discussed as part of this, to check the person having the test is well informed and wants the test.  These discussions can include ethical, legal and social issues. A genetics doctor or genetic counsellor can help you to consider things like possible insurance implications, emotional aspects of testing and results, talking to family members, as well as understanding inheritance, future health risks or options. Parents may give consent for a child to be tested if the results could benefit that child.

Private Genetic Testing

There are many reasons why someone may want a private genetic test.  Please contact our helpline or email us if you wish to discuss your situation.  We may be able to provide some options for you to consider. Please note that Genetic Disorders UK do not carry out or arrange genetic tests. 

The private testing details we pass on are usually offered by genetics specialists who have NHS experience. Genetic Disorders UK do not recommend or endorse any specific providers of private genetic tests. Other providers of private testing may be available.

If you wish to do your own research to look for private genetic tests here are some questions to consider:

  • How is the service arranged? Is a referral needed? What testing is possible? (this may depend on your personal or family medical history).
  • Which health care professional is involved? Can you have a face to face or Skype/WhatsApp consultation with a genetics doctor (clinical geneticist) or a registered genetic counsellor? 
  • Who will carry out the testing?  Is the laboratory accredited? Do they follow best practice guidelines?  Are they regulated by an independent body such as the
  • How will you receive the results? Will you get a copy of the report? What follow up care or onward referral is possible?  Is there a named person you can talk you if you need a discussion afterwards?
  • What is the cost and how are they paid?
  • Do you need to travel for a consultation or a blood test?
  • How will your genetic and personal data be stored and who has access to it?

Direct to Consumer Genetic Tests

These tests are offered directly, often through the internet using a sample kit sent by post.  These tests do not usually involve a healthcare professional.  They may relate to ancestry or health risks, or certain lifestyle factors.  They often state they should not be used for medical or diagnostic purposes.  We encourage anyone thinking about having this kind of test to consider what happens to their data afterwards (who has access to it), to consider the options for support or information if they have questions afterwards, and to weigh up the usefulness and accuracy of information being provided. 

Please feel free to contact Genetic Disorders UK through our Genetic Counsellor led helpline, or our contact form if you wish to discuss any issues relating to genetic testing.

Further reading about genetic tests

Details and support around antenatal tests (tests during a pregnancy)

Information about embryo testing and regulation of this service

A number of NHS clinics and private companies offer PGD/PGT.  The HFEA is the government’s independent regulator overseeing fertility treatment and research