BACKGROUND: Rapid advances in scientific research have led to an increase in 
public awareness of genetic testing and pharmacogenetics. Direct-to-consumer 
(DTC) genetic testing companies, such as 23andMe, allow consumers to access 
their genetic information directly through an online service without the 
involvement of healthcare professionals. Here, we evaluate the clinical 
relevance of pharmacogenetic tests reported by 23andMe in their UK tests.
METHODS: The research papers listed under each 23andMe report were evaluated, 
extracting information on effect size, sample size and ethnicity. A wider 
literature search was performed to provide a fuller assessment of the 
pharmacogenetic test and variants were matched to FDA recommendations. 
Additional evidence from CPIC guidelines, PharmGKB, and Dutch Pharmacogenetics 
Working Group was reviewed to determine current clinical practice. The value of 
the tests across ethnic groups was determined, including information on linkage 
disequilibrium between the tested SNP and causal pharmacogenetic variant, where 
relevant.
RESULTS: 23andMe offers 12 pharmacogenetic tests to their UK customers, some of 
which are in standard clinical practice, and others which are less widely 
applied. The clinical validity and clinical utility varies extensively between 
tests. The variants tested are likely to have different degrees of sensitivity 
due to different risk allele frequencies and linkage disequilibrium patterns 
across populations. The clinical relevance depends on the ethnicity of the 
individual and variability of pharmacogenetic markers. Further research is 
required to determine causal variants and provide more complete assessment of 
drug response and side effects.
CONCLUSION: 23andMe reports provide some useful pharmacogenetics information, 
mirroring clinical tests that are in standard use. Other tests are unspecific, 
providing limited guidance and may not be useful for patients without 
professional interpretation. Nevertheless, DTC companies like 23andMe act as a 
powerful intermediate step to integrate pharmacogenetic testing into clinical 
practice.