What are rare diseases?
29 February 2016
Associate Professor Carol Wicking is a biomedical researcher at The University of Queensland’s Institute for Molecular Bioscience (IMB), Director of the IMB Centre for Rare Disease Research and a member of the Scientific and Medical Advisory Committee of Rare Voices Australia.
Imagine it’s your child’s third birthday. You have decorated the cake and the party’s organised. But your son won’t be blowing out his candles or playing with his older sister. He can’t walk or talk and barely recognises his parents or sister. You’re desperate for answers but despite being sent to specialist after specialist, the doctors can’t tell you what is wrong. The only thing you know is that your child has a rare disease and may be one of the roughly one-third of children with rare diseases who don’t live beyond the age of five.
The definition of a rare disease varies, with the European Union defining it as a disease that affects less than 1 in 2000 individuals. This means there are 6000 to 8000 rare diseases. Many, but not all rare diseases affect children, and 80 per cent are genetic in origin.
Many of us know someone with a rare disease. This is because although they are individually rare they are collectively common – roughly 1 in 12 Australians are living with a rare disease. Most of us will have heard of some rare diseases, such as cystic fibrosis or Huntington’s disease, but the names of most will mean nothing to us because in some cases there may be only a handful of people affected by this disease worldwide. This, combined with the fact that even people with the same disease can have different symptoms, can make diagnosis of a rare disease very difficult.
A recent survey of adults with rare diseases in Australia suggests that some have waited 20 years or more for a diagnosis, and half were misdiagnosed at least once (Office of Population Health Genomics, Department of Health Western Australia). This situation can and must change, but for this to happen we need to overcome a commonly held perception that rare diseases don’t warrant the investment that more common diseases like cancer, diabetes or heart disease attract. Families with rare diseases can feel forgotten as they try to access life-saving drugs, diagnoses or treatment. Clinicians are frustrated as they strive to achieve the best outcome for their patients; and researchers are often questioned on the wisdom of devoting research funds to diseases that affect so few people.
There is absolutely no doubt that more common diseases warrant the support of both our healthcare system and research sector, but this support should be extended to all diseases regardless of the frequency. This is not only because each person with a rare disease deserves the same support as those with common diseases, but also because findings from studying rare diseases can greatly impact our understanding and treatment of more common diseases.
Fortunately, change is in the air for rare diseases; change that is driven by technological advances that allow scientists to sequence every gene or in some cases every one of the 3 billion base pairs that make up our DNA. You see, in many cases a rare disease may be primarily caused by a single mistake in one of these base pairs. Previously, finding this mistake was like looking for the proverbial needle in a haystack, except for those rare diseases where scientists had already identified the culprit gene most likely to carry the mistake. But with new technology we can potentially find these mistakes in a fraction of the time and cost compared to just 5 or 6 years ago. As a result, the past decade has seen an explosion in the number of rare diseases for which the underlying defective gene(s) is known. So why is genetic diagnosis still an issue for some and why is it so important?
In Australia genomic sequencing is not yet an integral part of the healthcare system. For some diseases where the rogue gene(s) is known, genetic testing may already be available, but for many the answer will lie in applying new technologies to sequencing all or a large number of genes. To date a number of such cases have been solved as part of ongoing research efforts, but this severely limits the reach of this exciting new technology into the rare disease community, and means that access in many cases has been fortuitous and not equally available to all. Fortunately this is changing, facilitated by the recent National Health and Medical Research Council funding of the Australian Genomic Health Alliance, an Australia-wide network of clinicians, scientists and health economic experts working towards integrating genomic medicine into the healthcare system. This is not a simple task – there are a number of technical, logistical and ethical issues to be considered, but it will happen.
Genetic diagnosis is important because knowing the underlying cause of a disease may inform future reproductive choices for families, and can provide hope in moving toward improved treatment and tailored disease management. But there is another reason that diagnosis is important. With diagnosis comes the chance to connect with other families with the same disease. In this context, social media has dramatically broadened the scope of rare disease support networks beyond our own neighbourhood and country to the entire world. This ability to connect with other families is particularly important for those with extremely rare diseases, with parents reporting the benefits of being able to discuss their child’s condition for the first time with often the only other people who deal with the same challenges on a daily basis. In some cases this contact has lead to changes in disease management, with life-changing consequences.
There is another reason that diagnosis is important. Knowing the gene that underlies a given disease can provide researchers with the clue they need to move towards new therapies. In some cases, decades of fundamental research may have already shed light on how this or related genes function; in others the function of the gene may be completely unexplored and in turn will require much research to unravel. In either case uncovering the genetic basis of a disease clears the way forward on a path now paved with new technologies that allow the exploration of gene function at a level never before possible. Amongst these technologies, the newest and perhaps most exciting is genome editing, which allows scientists to precisely mimic or correct disease causing gene changes in models of disease. The implications for this technology is immense, but like genomic sequencing itself it is subject to technical and ethical constraints that will limit its application outside a research setting for some time.
I have no doubt the future is brighter for many families living with rare diseases now and in the future. However, change will only happen with a dedicated National Plan for Rare Diseases that advocates for fair and equitable access to diagnosis, drugs and treatment for all those with rare diseases. Unlike most European countries, Australia does not currently have such a plan. Fortunately, a national alliance for those living with rare diseases, Rare Voices Australia, is gaining momentum in advocating for such a national plan. Real change will only come when a co-ordinated approach to tackling rare diseases is in place.
Today (Monday 29 February) is Rare Disease Day, where people living with or affected by rare disease, patient organisations, politicians, carers, medical professionals, researchers and industry come together in solidarity to raise awareness of rare diseases. To find out more, visit rarevoices.org.au