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The importance of rare diseases: from the gene to society
  1. John A Dodge1,
  2. Tamara Chigladze2,
  3. Jean Donadieu3,
  4. Zachi Grossman4,
  5. Feliciano Ramos5,
  6. Angelo Serlicorni6,
  7. Liesbeth Siderius7,
  8. Constantinos J Stefanidis8,
  9. Velibor Tasic9,
  10. Arunas Valiulis10,
  11. Jola Wierzba11
  1. 1Department of Child Health, University of Wales Swansea, Swansea, UK
  2. 2Foundation for Genetics and Rare Diseases, Tblisi, Georgia
  3. 3Service d'Hémato Oncologie Pédiatrique, Hôpital Trousseau, Paris, France
  4. 4Department of Pediatrics, Maccabi Health Services, Tel Aviv, Israel
  5. 5Pediatrician and Clinical Geneticist, Hospital Clinico Universitario “Lozano Blesa”, Zaragoza, Spain
  6. 6Genetica Clinica Pediatrica, Università Milano Bicocca, Milan, Italy
  7. 7Youth Healthcare, Meppel, The Netherlands
  8. 8Department of Paediatric Nephrology, P&A Kyriakou Children's Hospital, Athens, Greece
  9. 9Department of Paediatric Nephrology, University Children's Hospital, Skopje, Macedonia
  10. 10Department of Paediatrics, Vilnius University Faculty of Medicine, Vilnius, Lithuania
  11. 11Department of Paediatrics, Gdansk Medical University, Gdansk, Poland
  1. Correspondence to Professor John Dodge, Department of Child Health, University of Wales Swansea, Singleton Hospital, Swansea SA2 8QA, UK;{at}

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What exactly do we mean by a rare disease (RD), and why are they important for paediatricians? The definition used for public health purposes in Europe is that an RD is one which affects fewer than one citizen in 2000; in the USA it is fewer than one in 1250.1 There are estimated to be between 6000 and 8000 known RDs in the world, many of which are predominantly paediatric disorders. About 75% of the diseases meeting the criteria for RD affect children, and about 30% of all patients with RDs die before their fifth birthday.2 Approximately 80% of RDs have a defined genetic basis.2 The true incidence and prevalence of individual RDs are often unclear. When the condition is fatal in childhood or early adult life, the prevalence in the population (table 1) will be well below the birth incidence, and will not reflect the gene frequency. Thus, to take the familiar example of cystic fibrosis, the birth incidence in the UK is about one in 2500 live births, but the population prevalence is given as about one in 8000.

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Table 1

Some examples of estimated European population prevalence given on the Orphanet website (

Although individually rare, the cumulative burden of RDs is significant. RDs may affect as many as 30 million Europeans, with at least 3 million in the UK and 4 million in Germany, and this statistic has not been lost on the European Union (EU). A Committee of experts on rare diseases (EUCERD) was set up in November 2009 to assist and advise the European Commission, including, inter alia, drawing …

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  • Competing interests JAD is a Trustee of Genetic Alliance UK and chairman of the Medical Advisory Board of Shwachman-Diamond Support UK.

  • Provenance and peer review Not commissioned; internally peer reviewed.