Rare Diseases Knowledge

About Rare Diseases

The definition of rare disease differs from country to country, but it generally refers to diseases with between one to eight patients for every 10,000 people.[1]
The government of Hong Kong has not established any official definitions of rare disease. The lack of definition denies many patients of a timely diagnosis, publicly funded medication and adequate social support.

[1] Aronson, J. K. (2006). Rare diseases and orphan drugs. British Journal of Clinical Pharmacology, 61: 243-245. doi:10.1111/j.1365-2125.2006.02617.x

There are between 6,000 and 8,000 rare diseases that are now recognised by the international community, among which 467 were identified in Hong Kong as of 2016. New types of rare diseases continued to be discovered every year worldwide.[1]

[1] Chiu, A., Chung, C., Wong, W., Lee, S. L., & Chung, B. (2018). Healthcare burden of rare diseases in Hong Kong – adopting ORPHAcodes in ICD-10 based healthcare administrative datasets. Orphanet journal of rare diseases13(1), 147. doi:10.1186/s13023-018-0892-5

Nearly all rare diseases are caused of genetic defects or mutation.[1] These can be passed onto one generation from the other.
A very small minority of rare diseases can be caused by a variety of reasons including but not limited to rare forms of infection, allergies and environmental factors.
In many cases, the exact cause remains unknown.

[1] Abbott, A. (2011). Rare-disease project has global ambitions, 472: 17. doi:10.1038/472017a

Some rare diseases identified in Hong Kong include Mucopolysaccharidosis, Pompe Disease, Infantile Cutaneous and Articular Syndrome, Tuberous Sclerosis Complex, Myelofibrosis, Marfan Syndrome, Rett Syndrome, Spinocerebellar Ataxia, Fabry Disease, Gaucher Disease, Achondroplasia, various forms of Osteochondrodysplasias, C9ALS/FTD, Myotonic Dystrophy and Huntington’s Disease.

Most rare diseases are unfortunately without treatment. For a lot of pharmaceutical companies, the number of patients of specific rare diseases is too small for the research and development of orphan drugs to be cost effective. The development of treatment therefore relies on public funding, government initiatives and private donations, which makes it an uphill battle. Although most rare diseases cannot be cured, for many cases an early diagnosis and proper medication can help control the disease and drastically slow down deterioration.

Developing patient registry is the cornerstone of all medical research studies. Patient registries gather essential data for theoretic and clinical research. Since 2010, NRND has put in considerable effort in establishing a patient registry for SCA. Through the patient registry, dozens of patients obtained a definite diagnosis and new mutations have even been identified (See Our Research Project). The registry also gives researchers access to a larger gene pool, with which much research can be done to better understand the diseases. NRND hopes to expand the patient registry to other diseases, which will extensively aid researchers to study the underlying causes of rare diseases.

Another important facet of the work of NRND is of course the research and development of novel drug candidates. Apart from P3, AQAMAN and BIND , members of NRND have also discovered the following drug candidates and are assisting in their drug development:


For myotonic dystrophy type 1:
Oligomer 4  
PLG50-1/5, PDG50-1/5, PDLG50-1/5
1a and 2a
Ligand 3  
Ligand 5, 6 and 9  

For multiple polyQ diseases, such as Huntington’s disease and several types of spinocerebellar ataxias

Developing a new drug from conception to approval for marketing takes around 15 to 16 years.

Upon finding a novel drug candidate, which takes several years of research, pre-clinical studies are initiated to evaluate its potential effectiveness. These studies are carried out in vitro (within the laboratory) as well as in animals and would normally take 5-6 years.[1] This stage is called “pre-clinical studies” and makes up the everyday work of NRND. Once various parameters are assessed (safety, carcinogenicity etc), clinical studies will begin.

Clinical studies are phases of studies on human that focus on different pharmaceutical aspects. Phase 1 focuses on the safety of the drug candidate, its performance and effects on the body, and the determination of dosage. Phase 1 may take several months or more. Phase 2 focuses on the effectiveness of the drug, whether it does what it intends to on patients with the targeted disease and with what kind of side effects. This phase can take up to a few years. The third phase of clinical studies is to confirm the drug’s efficacy, evaluate safety and prove that regulatory requirements are met. It is an extensive process that typically takes several years, in multiple medical institutions and with as many patients as possible.[2] This drug can be marketed when the third phase clinical test is passed, and the drug approved. All three phases of clinical trials take eight to ten years on average.[3] Some drugs are required to undergo on-going post-market surveillance.

From initial discovery to the marketplace, introducing a new medicine successfully takes therefore 15 to 16 years. Many studies come to a halt during clinical studies because of scientific or bureaucratic hurdle. Indeed, only around 13.8% of drug development programmes make it from Phase 1 Clinical Studies to marketing, not to mention those that fail pre-clinical studies before clinical studies even begin.

[1] Coloma, Preciosa. (2013). Phase 0 clinical trials: Theoretical and practical implications in oncologic drug development. Open Access Journal of Clinical Trials. 5. 119-126. 10.2147/OAJCT.S32978.

[2] Institute of Medicine (US) Committee on Accelerating Rare Diseases Research and Orphan Product Development; Field MJ, Boat TF, editors. Rare Diseases and Orphan Products: Accelerating Research and Development. Washington (DC): National Academies Press (US); 2010. 5, Development of New Therapeutic Drugs and Biologics for Rare Diseases. Available from: https://www.ncbi.nlm.nih.gov/books/NBK56179/

[3] Coloma, Preciosa. (2013). Phase 0 clinical trials: Theoretical and practical implications in oncologic drug development. Open Access Journal of Clinical Trials. 5. 119-126. 10.2147/OAJCT.S32978.

An early diagnosis of inherited rare diseases often means a timely treatment and improved care for patients of rare diseases and their family. If you have family members who have histories of rare diseases, genetic testing can ensure an early diagnosis.

About NRND

Nexus of Rare Neurodegenerative Diseases (NRND) is a multi-disciplinary research network. NRND gathers a group of courageous scientists and clinicians with collegial and creative mindsets. We are devoted to unveiling novel genetic causes of rare neurodegenerative and neuromuscular diseases, to understand the pathogenesis of these rare disorders, as well as developing novel treatment strategies for these diseases. We provide up-to-date R&D information of rare neurodegenerative & neuromuscular diseases to patient support groups in the Asia-Pacific region.

The collaborators have been working together since 2012. The network was formalized and named NRND in 2018.

NRND helped develop a patient registry for SCA together with HKSCAA. Furthermore, Professor Chan and his colleagues have discovered and developed various novel approaches in treating different kinds of rare diseases. For more details of these projects, see “Our Research Projects”.

NRND is devoted to uncovering the underlying causes of rare diseases. Only when the pathogenic mechanisms of the diseases are understood can treatment strategies be developed. In this way, NRND takes upon itself to improve medical care for patients of rare diseases.

Thank you for your interest in NRND! Please visit this page to find out how you can support the work of NRND.

When diagnosed with a rare disease…

Being diagnosed with a rare disease is definitely a frightening experience for you and your family. However, it is important to know that you do not have to walk the journey alone. First of all, take the time to adjust and evaluate the situation. Join an organization which will connect you with other patients, with whom you can share information, support and experience. It is also important to learn about your disease and research as much as possible, through reading related materials and consulting a medical expert of the disease. Sign up for patient registries because they connect you with scientists who might be doing clinical trials. Last but not least, stay positive and do not hesitate to seek counselling when you are overwhelmed with grief and frustration.

The government subsidizes patients of six specified types of lysosomal storage disorder. The Community Care Fund Medical Assistant Programmes offer financial support for a small selection of rare diseases (For more information about the programme, see http://www.ha.org.hk/visitor/ha_visitor_index.asp?content_id=208076)

Patients groups such as Hong Kong Alliance for Rare Diseases and Hong Kong Spinocerebellar Ataxia Association offer community programmes that foster mutual help and self-empowerment.

Yes, participating in clinical trials can facilitate the development of treatments. You can first join a patient registry. Once clinical trials opportunities arise, you will be promptly contacted.

Join Us

Every contribution, no matter big or small, will directly impact the discovery and development of therapeutics for rare diseases – pathing the way to more break-throughs and saved lives.