“Rare diseases” (RD) are diseases which have very low prevalence and affect a small number of people. There are currently more than 8,000 known RD worldwide. Many RD are caused by genetic mutations or genetic defects. The age of onset varies from birth to old age, depending on the individual and disease type. The vast majority of RD pose a serious and long-term threat to patients’ health, and some can even be disabling and fatal.

Although the risk of having a rare disease is low, it is a risk that every new life needs to take. There are about 25,000 to 30,000 genes in the human body, and if a married man or woman has the same recessive disease-causing gene, or if one party has a family genetic history, or if the gene sporadically mutates, the next generation may experience RD with genetic abnormalities.

There is currently no uniform definition of RD that has been adopted unanimously around the world. For example, some overseas places have defined RD in terms of a prevalence rate measured by the total number of rare disease patients (less than 200 000 in the US and 20 000 or less in South Korea), the number of rare disease patients in 10 000 persons (fewer than five persons in the European Union and Australia, and fewer than one in Taiwan), or the proportion of rare disease patients in the total population (less than 0.1% of the total population in Japan)(Ref 1). Although China has not yet clearly defined a rare disease, the National Health Commission released in June 2018 "The First Catalogue of Rare Diseases in China" comprising 121 rare diseases; and in September 2023 "The Second Catalogue of Rare Diseases in China" including another 86 rare diseases with the relevant list of drugs and producers.

At present, ‘rare diseases” are referred to as “uncommon diseases” by the Hong Kong Government, and there is no official definition of “uncommon diseases”. Although not formally defined, there are indeed many RD cases in Hong Kong, of which more well-known ones include Mucopolysaccharidoses, Pompe Disease, Angelman Syndrome, Albinism, Marfan Syndrome, Rett Syndrome, Spinalcerebellar Ataxia, Tuberous Sclerosis Complex, Spinal Muscular Atrophy, Fabry Disease, Gaucher's Disease, Retinitis Pigmentosa, etc., most of which are genetic diseases. Although the number of cases of each rare disease is small, a study by the University of Hong Kong indicates that the total number of rare disease patients in Hong Kong is as high as 110, 000.

The challenges faced by rare disease patients in Hong Kong:

i. Lengthy process of diagnosis: due to the small number of cases and lack of awareness of RD among the healthcare professionals, countless patients have to go through a long and tiring journey before being diagnosed. These patients usually have to visit many different specialists or even send their samples overseas for laboratory tests in order to secure a diagnosis, but some of them can remain undiagnosed and untreated after a long time.

ii. Inexperience of healthcare professionals: The medical profession in Hong Kong has paid little attention to rare diseases and the resources pertaining to RD research and development are scarce, resulting in a serious lack of experienced medical staff for RD, which deprives patients of appropriate medical support. As most RD are caused by genetic defects, there are very few specialists in Hong Kong who are now trained in clinical genetics, so they simply cannot cope with the service needs of the patients.

iii. Drugs with high prices and poor access: The cost of research and development of orphan drugs (medications used to treat RD) is high, whereas the number of applications is small, so the price of orphan drugs is generally higher than ordinary drugs. Despite the fact that Hong Kong has a medical safety net and financial assistance mechanism, the Hospital Authority (HA) often emphasizes the importance of cost-effectiveness under the mechanism of its Drug Formulary, making it difficult for most of the orphan drugs, which can cost up to several hundred thousand to several million dollars per year and have fewer indications, to be listed on the HA Drug Formulary. Therefore, these costly medications are out of reach of the patients. Even though patients with better financial health can have access to the unregistered drugs under the Named Patient Programme, they will face heavy financial burden over the long term and may eventually become poor.

iv. A healthcare system that ignores differences: Hong Kong does not have any specific policy on provision of support for rare disease patients. As our healthcare system values equality and cost-effectiveness, patients with RD can only “equally” share the healthcare services with the majority of non-RD patients. Consequently, the special needs of the patients with RD are often ignored.

v. Different sources of mental stress: Due to the lack of public awareness of RD, many people have a certain degree of misunderstanding and prejudice against RD. So, patients with RD may suffer from social isolation. Work and studies are usually affected by the illnesses, coupled with the lack of appropriate and timely diagnosis and support. Therefore, many patients with RD are prone to guilt and self-blame, which may even lead to marital, social and mental problems. In some cases, the caregivers or parents are forced to give up their jobs because they need to take care of the patients on a long-term basis. Hence, the family financial burden will become heavier, and the caregivers will be physically and mentally drained or depleted. Studies have shown that the unemployment and poverty rates of families with RD are much higher than the average in Hong Kong.

Hong Kong has internationally recognized public health policies and a high-quality healthcare system, yet the prevention and treatment of RD and the protection of patients lag far behind those in Europe, the United States and its Asian neighbours. Therefore, RDHK has been committed to advocating for the Government to define ‘uncommon diseases’ or ‘rare diseases’ and to formulate health and supportive policies and plans tailored to the needs of people with RD.

（Ref 1）Soruce：https://www.legco.gov.hk/research-publications/chinese/1617fs06-supplementary-information-on-rare-disease-policies-in-selected-places-20170714-c.pdf