Rare Disease Categories
All diseases are categorised using the International Classifications of Diseases by the World Health Organisation. This is the gold standard for diagnostic health information.
Rare diseases occur across almost all of these disease categories. These include:
- Cancers, such as Diffuse Intrinsic Pontine Gliomas
- Diseases of the immune system, such as Primary Immune Deficiencies
- Diseases of the nervous system, such as Leukodystrophies
- Diseases of the circulatory system, such as Pulmonary Arterial Hypertension (PAD)
- Diseases of the respiratory system
- Diseases of the digestive system
- Diseases of the musculoskeletal system or connective tissue
- Diseases of the blood or blood-forming organs
- Endocrine, nutritional or metabolic diseases, such as Batten disease
- Diseases of the skin
- Diseases of the visual system
- Diseases of the ear or mastoid process
- Mental, behavioural or neurodevelopmental disorders
- Sleep-wake disorders
- Diseases of the genitourinary system
- Developmental anomalies
- Infectious or parasitic diseases
- Symptoms, signs or clinical findings, not elsewhere classified.
Using the ICD, version-11, each disease is assigned it’s own code, and this code is then used in public and private health sectors worldwide to identify new cases (incidence) and estimate the proportion of total cases in the community (prevalence). This helps health systems understand morbidity and mortality rates, assisting them in service provision and estimating associated costs. Support for rare diseases is a priority because the overwhelming majority of rare diseases do not have an ICD number, therefore, their true burden is grossly underestimated.