Genomic and genetic testing have the potential to reshape clinical practice and to fundamentally change the way we prevent, diagnose, treat and monitor illness.
Our understanding of the genetic factors underlying many diseases has expanded rapidly in recent years. This includes our understanding of rare, single gene disorders through to more complex multifactorial conditions.
Precision medicine uses genetic information and environmental and lifestyle factors to develop prevention and treatment strategies. In particular, it uses genetic knowledge to develop targeted treatments.
Precision medicine can involve:
- gene therapy
- targeted drug treatments
- targeted immune therapies
- screening and lifestyle modification to prevent disease in high-risk individuals.
This approach is already benefiting patients in many areas of health, particularly in rare disease and cancer treatment.
As research continues to investigate novel ways of treating genetic disease with specific and targeted therapies, precision medicine is likely to hold great benefit for many more people affected by genetic disorders.
What's the difference between genetics and genomics?
Genetics is the study of genes and how they work passing genetic information from parents to their children.
Genomics is the study of the genome, which is the full set of an organism's genetic instructions. It includes the way genes interact with each other and with the environment.
The benefits of a genetic diagnosis
Understanding the genetic basis of a disease can have significant impact for an individual and their family. A genetic diagnosis can be very powerful. It provides an understanding of why a person is affected by a condition and how it is inherited in a family. It can also give genetic relatives (who may be at-risk) options for screening and testing, and may enable reproductive options for future pregnancies.
Precision medicine for genetic conditions
In some situations, when a genetic diagnosis is understood, precision medicine can be used to develop treatment and management options that are targeted to the individual and their specific condition. Although many genetic conditions do not yet have specific treatments, this is changing as targeted therapies are developed through research and applied in clinical trials.
In rare diseases, specific treatment for single gene disorders that are targeted specifically to modify the gene or protein identified as causing the disease, has led to treatment for disorders that were once thought incurable. For example:
- Spinal muscular atrophy type 1
Without treatment, children with this neuromuscular condition often do not survive to their first birthday. Gene therapy and targeted drug therapies are now being used with very promising outcomes.
- Inborn errors of metabolism
An example is Gaucher disease. Specific enzyme replacement therapies have been developed based on our understanding of the underlying genetic changes and enzyme deficiency.
- Cystic fibrosis
Treatments are already available as Pharmaceutical Benefits Scheme approved therapies or through clinical trial sponsorship. Some treatments are targeted to the particular gene variants identified in the affected person.
- Inherited retinal eye diseases
An example is Leber congenital amaurosis (LCA), a family of congenital retinal dystrophies that result in severe vision loss at an early age. Children with LCA caused by a specific gene defect can now be treated with gene therapy to stabilise and improve vision.
In cancer management, genetic studies of patient cancer cells may allow the oncologist to choose chemotherapeutic agents that are most likely to be effective, rather than administering the same treatment regime for all patients.
Another precision medicine approach in cancer therapy is immune effector cell therapy, which engineers the patient’s own immune cells to treat their cancer.
Challenges in this area of medicine
Genetic testing has expanded rapidly. As technology has improved, the cost of testing has reduced, and the utility of genetic testing has increased.
Although access to genetic and genomic testing has improved, challenges include waiting times for genetic services, the cost of new therapies and the availability of clinical resources. The cost of testing has reduced in recent years but still presents a challenge for many families and health services.
Mainstreaming genetics and genomics
Genetic testing was previously facilitated through clinical genetic services by clinicians with genomics expertise. As the demand and utility of genetic diagnosis has expanded, many non-genetic physicians want to be involved in providing genomic testing for the benefit of their patients.
Mainstreaming genetic services into many subspecialty clinics is one way to facilitate access to timely and appropriate genetic testing. However, challenges to mainstreaming genomics include patient consent and genetic counselling regarding the implications and likely outcomes for the individual and their family, as well as considerations around insurance and the sharing of genetic information.
The Agency for Clinical Innovation’s Clinical Genetics Network and the Centre for Genetics Education have many resources for clinicians and consumers to learn more about genetic testing and its appropriate use.
About Dr Lisa Worgan
Lisa has more than 20 years of experience in clinical genetics, and currently works as a Clinical Geneticist for Sydney Local Health District, based at the Royal Prince Alfred (RPA) Institute of Precision Medicine and Bioinformatics. As head of the clinical genetics service at RPA she works across many areas including paediatrics, prenatal and adult clinical genetics. Lisa has been co-chair of the ACI Clinical Genetics Network for 18 months.
About Bronwyn Burgess
Bronwyn is a certified genetic counsellor with more than 25 years of experience in clinical genetics, including cancer genetics. Bronwyn is currently Head of Department and Manager at Hunter Genetics and works clinically three days a week in the general genetics service. She works across many areas including paediatrics, prenatal and adult clinical genetics. She has been co-chair of the ACI Clinical Genetics Network for 18 months.