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Genetic counselling and genetic testing: for patients

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What is genetic counselling?

When a patient or their child is diagnosed or suspected to have an inherited condition, or if there is a strong family history, they are normally offered to see a genetic counsellor who will help them in understanding: 

  • The genetic cause and its meaning
  • Risk to other family members and future generations
  • Family planning options 
  • Any genetic testing which may clarify the situation

The purposes of genetic counselling are: 

  • To provide support and information that a patient needs in a genetic clinic 
  • Promote informed and autonomous decision-making

It is a communication process of helping patients and their families to understand and adapt to the medical, psychological and familial implications of a genetic diagnosis or result. 

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What does the genetic counselling session involve?

Following the clinical determination by an ophthalmologist that a genetic eye disease may be present, a genetic counselling session usually follows which involves:

  • Taking a detailed family and medical history (also known as a pedigree)
  • Explaining and discussing genetic inheritance and the different possible inheritance patterns
  • Providing information on current research and helpful resources
  • A thorough discussion about the pros and cons of genetic testing or if it is indicated 

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What is genetic testing?

Genetic testing involves analysing changes in our DNA to identify the underlying genetic mutations causing the condition. It is a voluntary process where your genetic counsellor will go through the risks and benefits of testing before going ahead. If you choose not to go ahead with genetic testing, it will not affect your care under the National Health Service (NHS).

What does genetic testing involve?

If a patient/parent decides to proceed with testing, the following process ensues:

  1. Obtaining consent after a discussion about the risk and benefits of testing, and providing opportunities to voice out any concerns or queries 
  2. Taking a blood sample (or sometimes a saliva sample) from you and maybe from other family members as well
  3. Sending the samples for testing and analysis (may take up to several months to process) 
  4. Interpreting the genetic data in the context of the clinical findings (your symptoms and examination findings by your eye doctor) and assessing the likelihood of an identified genetic change as the underlying cause of your condition
A simple animation on genetic testing

Once the results are finalised, the findings will be explained and discussed with you either by letter, over the phone or at the next clinic visit. The genetic counsellor will highlight the individual and familial implications of the result such as the chances of the same genetic change occurring in other family members leading to the same condition (known as recurrence risk). If relevant, family planning options will be discussed and a referral to the local clinical genetics service is made. Occasionally, samples from other family members may be required in order to provide patients with more accurate advice and prognosis. 

Depending on the type of test utilised and the amount of data generated, it could take at least 6-9 months for results to be returned.

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Benefits of genetic testing

With the advancement of technology and increasing understanding of the human DNA, genetic testing is now more widely available and accurate, benefiting patients in multiple ways. These include:

  • Confirming the diagnosis of a specific genetic condition which sometimes may affect other organs as well and require input from other specialists, or where an established treatment is available (e.g. gene therapy for retinal degenerations due to mutations in the RPE65 gene)
  • Determining the prognosis of a specific condition 
  • Confirming the inheritance pattern and recurrence risk to other family members and future generations
  • Identifying relatives who are carriers (individuals having the same genetic mutation as the patient but not showing any symptoms) that can pass on the condition to their future generations. For example, those suffering from autosomal dominant conditions with reduced penetrance or at-risk female carriers of conditions inherited in an X-linked manner
  • Assist in family planning
  • Paving the way for participation in clinical trials of new treatments
  • Contributing to research where the discovery of new genes or specific genetic mutations will be informative for future diagnosis and clinical trials
A family’s experience with rare disease and how genetic testing helped with achieving a diagnosis

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Limitations of genetic testing

Although there are many benefits to genetic testing, there are still some limitations that patients should be aware of before proceeding with testing. These include:

  • Limited information– Sometimes the test cannot predict if a person will show symptoms, how severe the symptoms will be or whether the disorder will progress over time
  • Emotional implications associated with a genetic result including stress, sadness, anxiety and guilt (parents may feel they are responsible for their child’s diagnosis)
  • Creating tension within a family because results may reveal information about other family members in addition to the person who is tested
  • Plans of having children may be affected by a genetic result. A referral to a local clinical genetics service can be made to discuss about the available reproductive options
  • Concerns about the possibility of genetic discrimination in employment or insurance
  • Management of a condition may not necessarily change with a genetic result as there may not be any specific treatment strategies available
  • Ambiguity– Due to naturally occurring genetic variations between individuals called polymorphisms, it is sometimes difficult to tell if an identified genetic mutation that has not been associated with any conditions previously is a natural polymorphism or a new disease-causing mutation

A proportion of patients may have an “unsolved” or “negative” genetic result. This means that a genetic mutation was not identified with the applied testing method. This does not exclude that the condition is not due to a genetic cause, but rather it may be because of the following reasons: 

  • Limitations of current technology
  • Another testing method that provides more detail may be required 
  • Limited knowledge about the causative genes associated with that particular condition

If this is the case, the genetic counsellor will normally explain to you about the available options and how you could proceed. Sometimes, it may mean “banking” the sample and revisit it at a later time when there are new discoveries or improvements to the current technology. 

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Impact of genetic testing on employment and insurance

Insurance companies may ask you to provide medical information about you and your family. The information that you need to share is regulated by the ‘Code on Genetic Testing and Insurance’, which is an agreement between the Government and the Association of British Insurers (ABI). The purpose of this Code is to protect individuals from discrimination by insurers based on their genetic testing results.

You might be asked to tell the insurance company about the results of a diagnostic genetic test as the Code recognises that such a test is the same as any other diagnostic medical tests (such as a blood test). You will not, however, have to disclose the results of predictive genetic testing (testing undertaken by you or your family to assess the risk of having a specific genetic condition in the future), unless you are applying for life insurance over £500,000 and you have had a test for Huntington Disease as part of your care. 

Under the Code, the insurance company will not require nor can they pressure any applicant to undertake a predictive or diagnostic genetic test, nor ask for, or take into account, the result of any predictive genetic test obtained through scientific research. The NHS will not give your genetic test results to an insurance company without your consent. 

In terms of employment, employers are restricted about what they can ask about in pre-employment medical checks by the Equality Act 2010. They can only ask for information that is directly relevant to your ability to carry out the required work and they are mandated by law to make ‘reasonable adjustments’ to the workplace to enable you to work there

Related links

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Interested to be genetically tested?

There are a number of patients who have been diagnosed with an inherited eye disorder but did not undergo any genetic testing. If you are in a similar situation and would like to undergo genetic testing, you can ask your GP or ophthalmologist to refer you to the Moorfields Genetic Eye Disease service or the Great Ormond Street Hospital for Children Ophthalmology service.

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Further information

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