Incidental findings

Incidental findings are results that are returned from genomic testing that were not looked for as part of the original clinical investigation. They can have important consequences for the person receiving them and any possibility of incidental findings should be discussed with patients in advance of testing.

Examples of incidental findings include:

• A pathogenic variant in a gene associated with a condition unrelated to the one for which genomic testing was requested (for example, a breast cancer risk variant in a patient tested to find the cause of their epilepsy).
• Carrier status for an autosomal recessive disorder unrelated to the reason for testing (for example, cystic fibrosis).
• Misattributed family relationships (for example, non-paternity can be detected where individual and parental samples are sequenced simultaneously).

The more genes that are included in a test, the greater the likelihood of detecting an incidental finding.

When an incidental finding is returned from genomic testing, a group of healthcare professionals often come together as part of a multi-disciplinary team meeting to discuss key issues such as:

• what the clinical implications of the incidental finding are and how best to manage the patient; and
• whether the finding should be reported to the patient and/or their family.

The British Society for Genetic Medicine has published national guidelines to support decision-making around the return of incidental findings.

In this film, Sara recalls her daughter Freya’s experience of undergoing genomic testing to try to identify the cause of her learning disabilities. This testing looked not only at Freya’s genome, but at her parents’ genomes as well, to allow comparisons between them.

After the test results came back, it was not Freya but Sara herself who was identified as having a rare condition: Lynch syndrome, which predisposes to cancer.

Sara explains the importance of consent in this case – how clinicians made the family aware that incidental findings were a possibility and explained the impact this could have on them.

Note: As this testing was carried out as part of the 100,000 Genomes Project, Sara opted to have her genome analysed to look for clinically actionable variants, something which is not currently done routinely within the NHS Genomic Medicine Service. However, this type of incidental finding may still occur in routine testing.

Although many people feel positive about receiving information about an incidental finding, not all incidental findings are the same, and they can be extremely distressing. It is important to treat each situation with care and ensure that the family understands the potential implications of any test.

• There is a wide range of possible incidental findings that may arise from genomic testing.
• The possibility of incidental findings should be discussed with patients before testing.
• The more genes that are included in a test, the greater the likelihood of an incidental finding.

For clinicians

• The British Society for Genomic Medicine (BSGM): Guidance on Incidental Findings
• NHS England Genomics Education Programme (GEP): Genomics in the NHS: A Clinician’s Guide to Genomic Testing in Rare Disease