World Health Organisation: Rare diseases are a global health priority
for equity and inclusion
1 in 2000
AFFECTED
What is a rare disease?
- A specific health condition affecting 1 in 2000 individuals or fewer in the general population
- There are currently over 7000 known rare diseases impacting more than 300 million people globally, with 70% of these conditions starting in childhood
- They are often complex and multisystemic, affecting multiple organs
- They often lead to comorbidities
- Many of these conditions are chronic, progressive, and can consequently result in serious disabilities and premature death
- Reaching the correct diagnosis can take over five years, so many persons living with a rare disease never receive a timely or adequate diagnosis
Examples of Rare Diseases which might be seen in the uk working population:
Diseases that someone is born with:
Neurofibromatosis type 1 (NF1)
- Prevalence: ~1 in 3,000
- Genetic from birth;
often mild; highly variable symptoms
Marfan Syndrome
- Prevalence: ~1 in 5,000
- Genetic from birth;
connective tissue disorder; often diagnosed in
adolescence / adulthood
Hypertrophic cardiomyopathy (genetic forms)
- Clinically significant
congenital disease: ~1 in 2,000 - Often detected via family
screening
Neurofibromatosis type 2 (NF2)
- Prevalence: ~1 in 25,000
- Genetic from birth;
symptoms often later in life
Ehlers–Danlos syndromes (classical, vascular, rare types)
- Prevalence: Each subtype ~1 in 10,000
- Hypermobile EDS not included due to uncertain prevalence
Phenylketonuria (PKU)
- Prevalence: ~1 in 10,000
- Universal newborn screening in the UK
Diseases which are acquired during life:
Mesothelioma
- Exposure: Asbestos
- UK prevalence: ~1 in 10,000 (lifetime risk higher in older men, still rare overall)
- Why rare: Requires heavy historical exposure + long latency
Farmer’s lung (chronic hypersensitivity pneumonitis)
- Exposure: Mouldy hay/silage
- Prevalence: <1 in 10,000
- Why rare: Requires repeated sensitising exposure
Legionnaires’ disease
- Exposure: Water systems
- Prevalence: ~1–2 per 100,000 annually
- Lifetime prevalence: <1 in 2,000
Isocyanate-induced occupational asthma
- Exposure: Spray paints, foams
- Prevalence: <1 in 2,000
- Note: Severe but rare; high individual risk in exposed workers
Asbestosis
- Exposure: Asbestos
- Prevalence: Well below 1 in 2,000
- Note: Far rarer than pleural plaques
Chronic lead poisoning (clinically significant)
- Exposure: Old housing,
hobbies, renovation - Prevalence: <1 in 2,000
- Note: Low-level exposure is more common; disease is not
Leptospirosis (Weil’s disease)
- Exposure: Rat urine, freshwater
- Prevalence: ~0.1–0.2 per 100,000 annually