A disease is defined as rare if it has a prevalence of less than 5 per 100,000 . However, collectively, rare diseases are surprisingly common, creating a huge health-care and economic burden. There are an estimated 5000—8000 rare diseases, and about 5—8% of the European population is thought to be affected by a rare disease, many of which have neurological manifestations. About 80% of rare diseases have a genetic basis, and onset is often in childhood. Early diagnosis of neurological disorders is the key to halting disease progression. However, diagnosis of rare diseases can be challenging and is often delayed owing to limited knowledge about these conditions among clinicians, as well as difficulties in accessing specialized services.
Although rare diseases are by definition individually rare, collectively they affect millions of people worldwide. A united approach to tackling rare diseases, including pooling of financial and scientific resources, is essential to ensure that patients with rare diseases are given the priority they deserve.
– Written by Helen Frankish