Rare Disease Day 2014: 6 key questions about rare diseases

February 28 is International Rare Disease Day for 2014. To mark the day we offer answers here to 6 key questions about rare diseases and their treatment in the UK

1) What is a rare disease?

The UK’s Department of Health define a ‘rare’ disease as one which:

  1. has an incidence of less than 1 in 2000 people
  2. and is a life-threatening or chronically debilitating disease
  3. and requires special combined efforts to enable patients to be treated effectively.

 2) How many rare diseases are there?

We do not know for certain how many rare diseases there are. The Department of Health estimate that there are between 5,000 – 8,000 rare diseases. Some rare diseases are so rare that they are not well defined or understood yet. Around five new rare diseases are described in medical literature each week. However, more than 2000 rare diseases are already well characterised.

3) How ‘common’ are rare diseases?

Collectively, rare diseases are not rare. They affect 1 in 17 of the population at some point in their life. In other words, rare disease will affect over 3 million people currently living in the UK.

50% of newly-diagnosed cases of rare diseases are in children. According to Rare Disease UK, 30% of rare disease patients will die before their 5th birthday.

4) Do all rare diseases have a genetic ’cause’?

The majority of known rare diseases do have a genetic origin. Recent Department of Health and Eurodis publications suggest that around 80% of rare diseases have a genetic component, the vast majority being due to variations in a single gene or gene pair.

5) Can rare diseases be tested for?

Many rare diseases can now be diagnosed by specific genetic tests, although access to testing may need to be through a recognised specialist clinician.

Advances in genetic and genomic technology are enabling many more patients with a rare disease to be able to benefit from genetic tests. These can be either to:

  • establish or confirm a diagnosis; or
  • assess the genetic status of other family members.

We know that some rare diseases are caused by an alteration in just one or a pair of genes. When the gene responsible for the disease has been identified, it is possible to test the specific gene associated with the condition.

For many rare diseases there is diagnostic expertise in the UK, usually concentrated in one or a few centres. Additionally, for many conditions there is also an optimal management plan or treatment for the condition, usually informed by closely-linked research, and available through the expertise at the centres.

6) Where are testing and treatment available in the UK?

NHS Specialised Services is the national organisation responsible for the commissioning of specialised services that help improve the lives of children and adults who have very rare conditions. View their list of nationally-funded specialised services.

The UK Genetic Testing Network publish details of individual conditions for which genetic tests are available and of the centres which offer specialist clinics for those conditions.

If you would like to learn more about rare diseases, please visit the rare disease pages on the Centre website.

Rare diseases infographic