Rare diseases are individually uncommon, but collectively they affect millions of people. In the UK, around one in 17 people will be affected by a rare condition at some point in their lives, with 75% of rare diseases affecting children. There are between 7,000 to 8,000 known rare diseases. However, 6,000 children are born each year with a genetic condition so rare it does not have a name.
It is this rarity that presents a fundamental challenge: how do we understand something that appears only in small numbers, dispersed across hospitals, regions and clinicians?
National surveillance changes that.
The British Paediatric Surveillance Unit (BPSU) enables paediatricians across the UK and Republic of Ireland to report cases of uncommon conditions through an active monthly reporting system. By systematically gathering information on rare childhood disorders, the BPSU creates a national picture where none would otherwise exist.
Over four decades, this approach has generated substantial national evidence. The BPSU has received more than 38,000 reports of rare conditions, conducted over 140 surveillance studies, and contributed to more than 200 peer-reviewed journal publications and over 300 scientific presentations using BPSU data.
The impact of BPSU run surveillance studies are wide-reaching and is demonstrated well by looking at one of the BPSU’s longest run surveillance.
A 27-year case study: Progressive intellectual and neurological deterioration
In 1997, concerns emerged about whether variant Creutzfeldt-Jakob disease (vCJD) might affect children. Detecting such a rare but serious condition required more than individual clinical vigilance — it required national coordination.
The Progressive intellectual and neurological deterioration (PIND) study was established through the BPSU to monitor children presenting with progressive loss of intellectual and neurological function.
What followed was 27 years of continuous national surveillance — the longest-running study conducted through the BPSU.
Over nearly three decades, the PIND study brought together reports from across the UK, creating a comprehensive picture of rare neurodegenerative and metabolic disorders in childhood. It provided improved understanding of the incidence and causes of progressive neurological decline, and valuable clinical insight into presentation, and generated a unique longitudinal dataset spanning major advances in genetic and metabolic diagnostics.
The PIND study stands as a powerful example of what can be achieved through long-term national surveillance. It ensured that children with progressive neurological deterioration were not simply isolated cases in individual clinics, but part of a collective national understanding.
On Rare Disease Day, awareness is of course essential. But lasting progress also depends on something quieter and sustained: the ability to see the rare clearly, consistently and nationally. That is why surveillance is vital.
If you are a consultant paediatrician working in the UK, please sign up to the BPSU and support the surveillance of rare disease in children.
You can read more about the PIND study, or any of our other current surveillance studies.