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Practice Practice Pointer

Direct-to-consumer genetic testing

BMJ 2019; 367 doi: (Published 16 October 2019) Cite this as: BMJ 2019;367:l5688
  1. Rachel Horton, clinical training fellow1 2,
  2. Gillian Crawford, principal genetic counsellor1 2,
  3. Lindsey Freeman, senior clinical scientist3,
  4. Angela Fenwick, associate professor of medical ethics and education1,
  5. Caroline F Wright, senior lecturer4,
  6. Anneke Lucassen, professor of clinical genetics1
  1. 1Clinical Ethics and Law at Southampton (CELS), Faculty of Medicine, University of Southampton, UK,
  2. 2Wessex Clinical Genetics Service, Princess Anne Hospital, Southampton, UK
  3. 3Wessex Regional Genetics Laboratory, Salisbury, UK
  4. 4University of Exeter College of Medicine and Health, Exeter, UK
  1. Correspondence to A Lucassen a.m.lucassen{at}

What you need to know

  • Finding a “health risk” via direct-to-consumer (DTC) genetic testing often does not mean that a patient will go on to develop the health problem in question

  • DTC genetic tests might report false positives (artefacts)

  • “Reassuring” results from DTC genetic tests might be false negatives

  • Make sure you are confident in the provenance and interpretation of a genetic result before you base any clinical decisions on it

  • If your patient meets criteria for referral to clinical genetics, refer regardless of the results of their DTC genetic test

Direct-to-consumer (DTC) genetic tests are sold online and in shops as a way to “find out what your DNA says.”12 Testing kits typically contain instructions and equipment for collecting a saliva sample, which customers post to the DTC company for analysis.

Some DTC genetic tests promise insights into ancestry or disease risks; others claim to provide information on personality, athletic ability, and child talent. However, interpretation of genetic data is complex and context dependent, and DTC genetic tests may produce false positive and false negative results.

Anyone concerned about a result from a DTC genetic test might turn to their general practitioner (GP) or other primary healthcare provider for advice. This practice pointer aims to help clinicians in this scenario and explains what sort of health information is provided by these tests, their limitations, and how clinicians can respond to common questions about them.

What is a DTC genetic test?

Most DTC genetic tests don’t sequence the whole genome. They typically use a method called SNP-chip genotyping, which checks for the presence or absence of specific variants throughout the genetic code, such as particular single nucleotide polymorphisms (SNPs), or small insertions or deletions. SNP-chip genotyping detects common genetic variants well, but when SNP-chips detect very rare variants these are often false positives (ie, they are not really present …

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