Your genome is the instructions for making and maintaining you. It is written in a chemical code called DNA . Your genome is all 3.2 billion letters of your DNA.

Inside almost every cell of your body is a copy of your genome, made of DNA. The genome can be thought of as the instructions for running a cell. It tells the cell what kind of cell to be – is it a skin cell or a liver cell? It also has the instructions that tell the cell when to grow and divide, and when to die.

When a cell divides to become two cells, your genome is copied. Usually, our cells divide to make new cells in a controlled way. This is how our bodies grow and repair. Sometimes when our cells divide, mistakes happen when copying the genome. They are caused by natural processes in our cells, or just by chance. The differences are called ‘variants’. These might be a single letter. Or a string of letters may be in a different place or missing. 

Whole genome sequencing will involve samples being taken, sent to a laboratory, run through a machine that ‘reads’ the DNA and a report will be returned to your clinical team with any relevant findings. As you share your DNA with family, getting tested may have implications for other members of your family, so you may want to think about if you want to share that information with them and talk to them about what it might mean for them following your results.  

 Results can provide information on:

• genes that have not previously been looked at through routine testing
• why your tumour or cancer developed 
• what type of tumour or cancer you have and check that you are receiving treatment tailored to your cancer. There may be clinical trials looking for patients with specific genetic changes in their tumour
• how Whole Genome Sequencing results may be used in treatment planning for the future 
• whether you have a gene which might increase your risk of developing other cancers in the future. You may be able to take precautionary action or start screening for the cancer sooner 
• whether other family members may have a greater risk of developing cancer and are able to get tested or start screening early

WGS for cancer patients – genome-sequencing-cancer-patient-information.pdf (england.nhs.uk)

Information for children and their parents – whole-genome-sequencing-for-children-NHSE.pdf (cclg.org.uk)

Information sheet for the National Genomic Research Library – https://files.genomicsengland.co.uk/documents/Genomic-Research-Patient-Information-v1.2-Dec-2020.pdf