13 August 2014
New research suggests that detection of Creutzfeldt-Jakob disease (CJD) could become much easier, thanks to non-invasive testing.
What is CJD?
CJD is a form of prion disease, a group of related progressively neurodegenerative (and eventually fatal) conditions known as transmissible spongiform encephalopathies. Prions are proteins that can acquire an abnormal shape, and are able to affect other prion proteins so that they too, form an abnormal shape, with detrimental effects. Misfolded prion proteins therefore act in the manner of an infectious agent in the transmission of prion diseases.
Whilst there are inherited forms of CJD caused by mutations in the PRNP gene, most cases are either sporadic (classical CJD) or acquired, such as variant CJD. Variant CJD (vCJD) is the human form of the infamous bovine spongiform encepaholopathy (BSE), also dubbed ‘mad cow disease’.
Non-invasive detection of CJD
A paper published in the New England Journal of Medicine reports a method for the detection of different forms of CJD based on the analysis of urine. A second paper also reports on the diagnosis of classical CJD based on the analysis of nasal cells. Both forms of testing were able to distinguish patients with CJD from other forms of neurodegenerative disease and healthy control subjects, using a form of protein misfolding amplification and detection.
Non-invasive diagnosis would not only make it much easier to definitively diagnose CJD, but also to monitor disease progression and response to potential treatments, as well as checking on the safety of donated blood and tissue for transplantation. Currently, definitive diagnosis of CJD requires an invasive brain tissue or spinal fluid biopsy (with disposal of all surgical instruments used, since they pose an infection risk; prions resist conventional decontamination procedures). A similar approach might even prove useful for the diagnosis of other neurodegenerative conditions that involve protein misfolding, such as Alzheimer's disease.
UK challenges in the control of variant CJD
Researcher James W. Ironside of the National CJD Research and Surveillance Unit at the University of Edinburgh observed that their new findings paved the way for “a screening tool for variant Creutzfeldt-Jakob disease infection in asymptomatic individuals, which is a topic of current interest in the United Kingdom”. Whilst most forms of CJD are very rare indeed, vCJD is more common in the UK, where it is thought to have originated via consumption of contaminated beef.
A recent report from the House of Commons Science and Technology Committee accused the UK government of complacency and inaction on the prevention of vCJD. Whilst fewer than 200 people have developed the disease to date, it has been estimated that one in two thousand people may be carriers. In their report, MPs sharply criticised government ministers for doing too little to support development or implementation of effective screening or sterilisation procedures for vCJD, and called for improved risk assessments.
Lessons for health policy
The apparent failures of the UK government to capitalise on earlier discoveries related to vCJD are a sobering illustration of the importance of doing more than throwing research funding at a problematic health issue. This is of course vital, and can lead to potentially transformative discov eries such as the new non-invasive tests; however, it is not sufficient. Rather, new tools must be evaluated not only for their scientific and clinical validity and utility, but also for their potential impact on current health systems and services.
Effective implementation of science to generate actual health benefits requires careful consideration of the regulatory and clinical environment along with a host of associated issues to develop policy that will underpin funding and uptake of an innovation in the relevant clinical and public health systems.
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