What is genomics?
Genomics is the study of the genes in our DNA, their functions and their influence on the growth development and working of the body.
Genomics Vs Genetics
Genetics is the study of genes, a unit of inheritance and its effect on an individual's health whereas genomics is the study of all the individual's genes and DNA (the genome) and its interaction with the environment.
Genomics in the NHS
In 2018, NHS England and NHS Improvement launched the Genomic Medicine Service (GMS), and In 2022, published a 5 year strategy ( Accelerating genomic medicine in the NHS) for embedding genomics across the NHS. This strategy aims to ensure equal access to the power of genomics in predicting, preventing and diagnosing disease, and targeting treatment as part of routine healthcare.
Genomics and cancer
Cancer is a genetic disease cause by changes in genes which control cell growth and multiplication. One of the key priorities of the NHS Genomics Strategy is being able to deliver equitable testing for improving outcomes in cancer, rare, inherited and common diseases and in enabling earlier diagnosis, targeted treatments and personalised care.
Inheritance / Family History
While most cancers are not due to inheritance, It's estimated that around 5 – 10% of all cancers diagnosed are linked to an inherited gene variant (Macmillan, 2023) but the numbers may be much lower than this for some types of cancer.
Inherited genes and cancer types
Genetic information is inherited from our parents in our DNA. This means that changes in gene function may also be inherited. Some of these changes (gene mutations) may increase the risk of developing certain types of cancer.
For more information about genetic conditions and inherited cancer syndromes, please visit : Family history, genes and cancer risk | Macmillan Cancer Support & Inherited genes and cancer types | Cancer Research UK
Lynch syndrome is an inherited genetic condition that can significantly increase the risks of developing certain types of cancer. The main risks are of colorectal cancer (up to 80% lifetime risk) and endometrial cancer (up to 60% lifetime risk). Other cancers associated with Lynch syndrome include ovarian, gastric, urothelial, small bowel and central nervous system, but these are much lower risks.
Gene variants
Inside every cell in our body is a set of genes which give instructions on how the cell should function, If genes are altered then they may not give the correct instructions. These gene changes are called gene variants or gene mutations. Lynch Syndrome is caused by a variant in one of the mismatch repair genes (MLH1, MSH2, MSH6 and PMS2) that usually correct errors in the replication of our DNA. Another gene called EPCAM can also be involved in Lynch Syndrome.
Inheritance
Lynch syndrome is inherited in an autosomal dominant manner. in simple terms, this means that if one parent carries the gene variant then each child has an individual 50% risk of inheriting the variant, therefore also having Lynch syndrome.
Diagnosis
Testing begins with looking at tumour tissue within the laboratory - the pathologists will look for changes in the mismatch repair genes. If this initial testing suggests that Lynch syndrome is a possibility then diagnosis can only be confirmed with a blood test. National guidance now recommends that all newly diagnosed colorectal and endometrial cancers receive initial tumour screening for Lynch syndrome as these are the most strongly associated.
Genetic testing
If this is required, then a healthcare professional will discuss the implications of the test and the possible outcomes. Genetic test results usually take around 2 months to process and report at which point another appointment will be required. There are three possible outcomes of Lynch syndrome genetic testing:
- Positive - a genetic change for Lynch syndrome is identified. This means a Lynch syndrome diagnosis is confirmed and the likely cause of the cancer. Additional therapies may be considered, surveillance will be recommended and predictive genetic testing will be offered to first degree relatives (parents,siblings & children).
- Uncertain - a genetic change (or variant) of unknown significance is identified. This means a genetic change is found but it is uncertain whether it caused the cancer. Further tumour testing may be advised in this instance. Family members would not be offered genetic testing at this point but surveillance for the individual and their family would be recommended.
- Negative - no genetic changes were identified. It is important to remember that this doesn't rule our an inherited condition. Further testing may again be recommended. Family members would not be offered genetic testing at this point but surveillance for the individual and their family would be recommended. Developments in genomics are rapidly advancing and the knowledge of
The West Yorkshire & Harrogate cancer alliance hosted an educational event in October 2023.
