Genomics in Primary Care

While genetics looks at individual genes, genomics refers to the study of all of an organism’s DNA and can provide a more holistic view of health and disease. 

Scientists study changes to the DNA of individuals that can cause conditions such as rare disease or inherited cancer syndromes, as well as changes to the DNA of bacteria – such as MRSA – to provide the best care to patients. 

There are dramatic advances being made in the field of genomic medicine and this will increasingly impact on primary care. 

Primary care is the gateway to the National Health Service; primary care practitioners are vital to the early identification of genomics issues and to ensuring appropriate management and quality of care. 

So-called ‘direct to consumer testing’ – where people access genetic testing themselves online or via a local chemist is becoming increasingly common; primary care will be the first port of call for people who have received results concerning themselves or their relatives and want to discuss them. 

Genomics plays a role in many conditions seen in primary care every day, including: 

  • so-called ‘rare diseases’, which actually affect 1 in 17 people  
  • chronic (common complex) conditions such as cancer and diabetes

Continue to use core primary care skills in risk assessment, managing emotional consequences, holistic management and care co-ordination of the patient and their family when dealing with genomics issues or questions.  

Think genomics. Know when to ‘spot red flags’: 

  • Take a family history to identify and understand the risk of inherited genetic conditions and cancers. 
  • Know how to recognise the early signs of rare disease in children – such as developmental delay. 
  • Consider genomics where a patient has a surprising test result – such as unusually high cholesterol with no other explanation. 

Know when and how to refer patients for specialist advice; know where to find up to date referral criteria. 

Be aware of the spectrum of support available to patients; this may include support groups, patient groups and third sector and voluntary organisations in addition to NHS care.  

Cancer 

  • Some individuals carry gene variants that make them more susceptible to certain types of cancer. For example, a BRCA1 gene variant may mean someone has an 80% lifetime risk of developing breast cancer; familial adenomatous polyposis results in up to 100% risk of developing bowel cancer.  
  • Only 5% of cancers are currently believed to be attributed to an underlying inherited cancer syndrome; most family histories therefore don’t put patients at increased risk. 
  • Individuals may receive cancer treatments tailored to a genomic test result, for example Herceptin for HER2 positive breast cancer. 
  • The number of people eligible for testing is increasing all the time. 

Rare, inherited conditions 

  • There are thought to be over 7,000 rare diseases, the majority of which are inherited. Signs are usually seen in childhood. 
  • Genetic testing plays a role in diagnosing rare diseases and in directing the management of the patient and their family. 
  • Genomics, through whole genome sequencing, is beginning to provide answers for increasing numbers of patients who previously had no diagnosis. 
  • The number of people eligible for testing is increasing all the time. 

Pharmacogenomics 

  • It’s estimated that only 50% of medications prescribed are effective; and adverse drug reactions have a significant impact on the NHS. 
  • Pharmacogenomics – the application of genomics in prescribing - helps identify the right drugs for patients and predict whether a patient is likely to have a side effect or adverse event as a result of medication. 
  • An example of pharmacogenomics in primary care prescribing is the use of SCLO1B1 gene variants to predict those at higher risk of developing myopathy on Simvastatin. As scientists learn more about genomics and more drugs are developed pharmacogenomics is predicted to impact increasingly on primary care prescribing. 
  • Patients can now access genomic testing themselves and may bring results to the primary care team. 
  • Test result may show an increased chance of developing a condition such as diabetes or cancer, or may also show a patient to be a carrier of a genetic condition such as cystic fibrosis. 
  • Results are of varying reliability and validity and patients should be managed in the same way as any other patient within the NHS – risk assessed via family history, and managed and referred as per usual NHS pathways and clinical care.  
  • A key role of the primary care practitioner is managing the emotional consequences of the genomics test result and providing guidance and reassurance as necessary; particularly if it is not deemed clinically actionable within the NHS. 
  1. A 37 year-old woman, Sally, comes to discuss family history of cancer: mother and grandmother had both died due to breast cancer. 
  2. A family history is taken to assess Sally’s risk, according to criteria her risk is above-population. 
  3. Refer Sally to the breast clinic. 
  4. While waiting for her first appointment, Sally contacts relatives and discovers that her cousin (maternal uncle’s daughter) has recently been diagnosed with ovarian cancer.  
  5. In light of this information, the breast clinic refers Sally to genomic medicine centre for consideration for testing. 
  6. Sally then contacted by genomic medicine service to ask for further details regarding family history. 
  7. Sally contacts cousin, who had previously has testing and was found to carry a BRCA1 pathogenic variant. This had implications for cousin’s cancer treatment plan. 
  8. Genomic medicine service explains to Sally that her uncle (father of her cousin) will need to be offered testing first, to establish whether he has the same BRCA1 variant. 
  9. Sally then offered testing and found to carry the same BRCA1 variant. 
  10. Implications for screening, risk-reducing surgery, contraception and children discussed with Sally. 
  11. Sally’s sister, Emma, presents requesting referral for testing.  
  12. Emma found not to be a carrier, meaning that even in the presence of a significant family history she could be reassured she was not at increased risk, and would not need screening until she was invited to the NHSBSP.   
  13. Emma struggles with feelings of guilt due to not having to deal with the same issues and difficult decisions as her sister, alongside anxiety as she no longer is eligible for breast screening and at an earlier age, and needs support from her GP in dealing with this.