Clinical genomics is a new and rapidly-changing field. Knowledge of the human genome is far from complete, but there are already uses for genetic and genomic information in the clinic.
Genome sequencing is expected to have the most impact in:
- characterising and diagnosing rare and inherited disease;
- stratifying individuals’ tumours to guide treatment (precision medicine);
- providing information about an individual’s risk of developing disease or their likely response to treatment (health management)
Characterising and diagnosing inherited disease
Every baby born in Australia is offered screening for approximately 30 genetic conditions (the Guthrie test) and more than 300 tests for genetic disorders are available through the healthcare system.
Clinicians worldwide are beginning to embrace genome sequencing to search for variants implicated in undiagnosed genetic diseases and using this information to guide treatment. In one of the most dramatic cases, a young boy underwent a risky, but seemingly successful, bone marrow transplant that was proposed in response to molecular data.
Stratifying cancer for better treatment
A major focus of genomic medicine is cancer diagnosis and therapy. Clinicians are beginning to use genomic information to predict how a person's cancer will respond to drug therapy or surgery. In some cases, clinicians will profile the DNA and RNA of tumour cells to guide the use of existing treatments or focus on more targeted treatments.
At this stage, some patients have been spared costly and complex procedures based on a molecular diagnosis. Tumour development in a few patients has been stabilised – for a time, at least – by targeting specific molecules or pathways in tumour cells.
The Genomic Cancer Medicine Program, led by the Head of Garvan’s Cancer Division and Director of The Kinghorn Cancer Centre, Professor David Thomas, is a research program dedicated to applying genomics to the understanding, early detection, prevention and management of cancer. This program was established as part of the Sydney Genomics Collaborative, a $24 million, four-year investment by the NSW State Government in using genetic technologies to improve patient outcomes.
Health management: understanding disease risk and predicting drug response
The application of genomic medicine is not limited to typically genetic conditions. All diseases have a genetic component, from inherited conditions to complex diseases such as cancer and diabetes. Different people also react differently to parasites, viruses and bacteria according to the information encoded in their genome.
Beyond diagnosis and guiding patient management, the major value for genomics in health is expected to be in: understanding an individual’s disease risk; detecting disease early, and, ultimately, preventing disease. Researchers are identifying a broad range of variants – across the genome – that are clinically useful.
Individuals’ genetic differences are also thought to be responsible for up to 80% of adverse reactions to drugs and genetic tests for variants involved in drug metabolism are increasingly used in Australia. Comprehensive profiles of an individual’s genetic data, integrated with common clinical markers, are expected to provide new insights into disease.
Additional references and commentaries
- Dinger M, Terrill BN (2016). A user’s guide to the human genome (PDF). O&G Magazine.
- Gaff C. and Waring P (2014) Cheap genome tests to predict future illness? Don’t hold your breath. The Conversation.
- Somogyi A (2013). Pharmacogenomics explains why some medicines may not work for you. The Conversation.
- Check Hayden E (2011). Genome study solves twins' mystery condition. Nature. doi:10.1038/news.2011.368.
- Johnson M, Gallagher K (2010). One in a Billion: A Boy's Life, A Medical Mystery. JSOnline: Milkwaukee Wisconsin Journal Sentinel.
- National Health and Medical Research Council (2011). Clinical Utility of Personalised Medicine. (PS0001). Australian Government.
- Maher B (2011). Human genetics: Genomes on prescription. [News Feature]. Nature 478:22-24. doi: 10.1038/478022a.
- Mardis ER (2010). The $1,000 genome, the $100,000 analysis? Genome Medicine 2:84.