Royal College of General Practitioners guidance places significant doubt on consumer genetic testing.
Consumer interest in genetic testing has grown in popularity in recent years, and sales of testing kits are booming, with the market set to hit $6.36 billion by 2028 . Genetic testing kits are intended to provide consumers with information about their DNA, ancestry, future health and Longevity, without having to go to their doctor.
Guidance on direct-to-consumer genomic testing published in a joint statement by The Royal College of General Practitioners and the British Society for Genetic Medicine stated :
“… health professionals should exercise caution when asked to offer, or provide, clinical expertise about the results of Direct to Consumer (DTC) genomic or genetic testing. The analytical validity, sensitivity and clinical utility of such testing may be much lower than is popularly perceived. For certain types of DTC results, there is a very high chance of false positive or false negative results.”
The guidance should be of interest to investors and potential investors into companies offering such services. Companies such as 23andMe, which received $300m investment from GlaxoSmithKline in July 2018, and Color Genomics are two of the leading players in this sector, now being joined by a host of new start-ups focused on consumer genetic testing .
The consumer testing kits promise to unravel the secrets behind a person’s DNA from a biological sample such as saliva, which is then sent to the company for analysis. Some companies claim to provide insight into risks of particular diseases, while others go a step further and claim tests that can reveal information on personality and talent.
Some may see consumer genetic tests as a potential preventive measure against disease and a way to get useful information without having to visit numerous medical professionals. However, understanding and extrapolating the genetic data and its meaning is a complex process and consumers may end up re-directing their results to physicians to help decipher them. Most consumer genetic tests do not sequence the whole DNA, they look for specific variants or lack thereof in the genetic code. The results can often show false positives, presenting elements that are not actually present in the person’s DNA. 
The official guidance goes on to say:
“Gene variants giving information regarding single gene conditions or predispositions: examples may be variants in breast cancer related genes (BRCA1 or BRCA2), or the Cystic Fibrosis gene (CFTR). Results may be:
- False negatives: The genes may have many different types of variation within them, yet often DTC testing only looks for a small proportion. Thus testing will miss a large proportion of these, for example in the region of 80% of known BRCA1/2 mutations are missed by commercial companies who generally only analyse three of the many different possible mutations.
- False positives: DTC tests that use a “SNP chip ” [single nucleotide polymorphism] technique [used by the majority of companies in operation in 2019] are very likely to categorise rare variants wrongly2. Thus 85-95% of BRCA1/2 variants or Bowel cancer gene variants for example, will be false positives or artefacts. The impact of false positives will likely place increasing demand on the health service which will need to spend considerable time and money counselling patients and reanalysing their samples.”
In addition to questions about the quality control for consumer genetic tests, there is also the question of how safe a consumer’s data is. As vital personal health information is collected, it is important to know what happens to the data after the results are provided. Last year, a Fast Company report indicated that 23AndMe and Ancestry were being investigated by the Federal Trade Commission over policies regarding data security and personal information sharing .