A rare disease occurs in less than 200,000 individuals in the United States, or less than 5 per 10,000 individuals in the European Union. Some diseases are widespread in certain parts of the world but rare in others. Source: Rare Diseases: Basic Information (rarediseases.about.com)
Causes
While most of the genetic diseases are rare diseases, all rare diseases are not caused by genetic defects. There are very rare infectious diseases for instance, as well as auto-immune diseases and very rare poisonings. The cause remains unknown to date for most diseases . Source: ORPHANET - About rare diseases - About orphan drugs (orpha.net)
Epidemiology
There are thousands of rare diseases. To date, six to seven thousand rare diseases have been found and five new diseases are described every week in the medical literature. This number also depends upon the accuracy of the definition. A disease has been defined as a state of dysfunction of one or more body systems. Whether a single pattern is considered unique depends on the state of our knowledge, on the accuracy of clinical and investigative analysis and on the way we choose to classify diseases in general. Source: ORPHANET - About rare diseases - About orphan drugs (orpha.net)
Prevention
Newborn screening can be performed to pick up on any rare disease and associated preventable complications. Newborn screening tests take place before your newborn leaves the hospital. Babies are tested to identify serious or life-threatening conditions before symptoms begin. Such diseases are usually rare. However, they can affect a baby's normal physical and mental development. Most tests use a few drops of blood from pricking the baby's heel. A hearing test involves placing a tiny earphone in the baby's ear and measuring his or her response to sound. If a screening test suggests a problem, your baby's doctor will follow up with further testing. If those tests confirm a problem, the doctor may refer you to a specialist for treatment. Following your doctor's treatment plan can save your baby from lifelong health and developmental problems. Source: MedlinePlus: Newborn Screening (nlm.nih.gov)
Symptoms
Rare diseases are serious chronic diseases, and often life-threatening. Signs may be observed at birth or in childhood, as in proximal spinal muscular atrophy, neurofibromatosis, osteogenesis imperfecta, chondrodysplasia or Rett syndrome for instance. However, more than 50 % of rare diseases appear during adulthood, such as Huntington disease, Crohn disease, Charcot-Marie-Tooth disease, amyotrophic lateral sclerosis, Kaposi's sarcoma or thyroid cancer . Source: ORPHANET - About rare diseases - About orphan drugs (orpha.net)
Treatment
The so-called 'orphan drugs' are intended to treat diseases so rare that sponsors are reluctant to develop them under usual marketing conditions. The process from the discovery of a new molecule to its marketing is long (10 years in average), expensive (several tens of millions of euros) and very uncertain (among ten molecules tested, only one may have a therapeutic effect). Developing a drug intended to treat a rare disease does not allow the recovery of the capital invested for its research.
Orphan drugs may be defined as : Drugs that are not developed by the pharmaceutical industry for economic reasons but which respond to public health need. Actually, the indications of a drug may also be considered as ' orphan ' since a substance may be used in the treatment of a frequent disease but may not have been developed for another, more rare indication. Source: ORPHANET - About rare diseases - About orphan drugs (orpha.net)
Treatment for periodic paralysis Sansone V, Meola G, Links TP, Panzeri M, Rose MR. (Details: open / close)
Background: Primary periodic paralyses are rare inherited (genetic disorder) muscle diseases characterised by episodes of weakness affecting one or more limbs, lasting several hours to several days.
Objectives: To review available treatment of periodic paralyses.
Method: Study groups were chosen from a wide database. Any form of treatment, including physical therapy and alternative therapies were compared with placebo (substance having no pharmacological effect) or another treatment.
Results: In one study, Dichlorphenamide (DCP) was tested with a placebo. There were two groups of participants (those with periodic paralyses with low blood potassium and those with high blood potassium). The majority of both these groups preferred DCP. Acetazolamide proved to improve muscle strength in eight participants with low blood potassium type periodic paralysis in one other study. Pinacidil, a potassium channel opener, also improved muscle strength in 2/4 participants with low blood potassium type periodic paralysis in a third study.
The above is a summarization of the following article: Full reference of the article: Sansone V, Meola G, Links TP, Panzeri M, Rose MR. Treatment for periodic paralysis Cochrane Database of Systematic Reviews 2008, Issue 1. Art. No.: CD005045. DOI: 10.1002/14651858.CD005045.pub2
1) Worldwide, there are an estimated 6000 to 7000 rare diseases. Patients face special difficulties in obtaining an accurate diagnosis, adequate information about the disease, and access to qualified specialists. (2) Drug companies do not spontaneously conduct research on drugs for rare diseases, mainly because of the limited market for each indication. Only a few dozen of these drugs were available in France before 2000. (3) In 2000 the European Union adopted a Regulation, based on experience in the United States, aimed at promoting the development of drugs for patients suffering from rare diseases, i.e. 'orphan drugs'. (4) In Europe, orphan drug status can be granted when the prevalence of the disease does not exceed 5 cases per 10 000 inhabitants (or when it is more frequent but profitability is likely to be inadequate). (5) Companies that market an orphan drug receive a variety of financial assistance as well as a 10-year marketing monopoly. (6) Between April 2000 and April 2005, 268 medicinal products received European orphan drug status and 22 were granted European marketing authorization. (7) Access to these drugs varies greatly from one European Union Member State to another, mainly because of the high annual treatment costs (up to 300 000 euros per patient). Worldwide sales of the orphan drug imatinib reached more than two thousand million dollars in 2005. (8) Our systematic analyses (see the New Products column of our French edition la revue Prescrire) show that only 5 drugs which received European orphan drug status before May 2005 were for diseases for which there had previously been no treatment. (9) Clinical evaluation of orphan drugs is hindered by the small number of patients available for clinical trials. Some orphan drugs are adequately tested before being brought to market. Others are not compared to existing treatments. In many cases, surrogate criteria are used instead of clinical endpoints. These methodological flaws are in no way limited to orphan drugs. (10) Not all orphan drugs represent therapeutic advances. Clinical research and evaluation should continue after marketing authorization has been granted. (11) More drugs, with better-documented efficacy and safety, are now available for patients who previously had no effective treatment options. Yet there is too much duplication and too little evaluation, and too many drugs are extremely expensive, meaning that patients in many European countries cannot benefit. And many rare diseases are still neglected.
Full reference of the article: No authors listed "Drugs for rare diseases: mixed assessment in Europe" Prescrire international, February 2007
Disorders resulting from inborn errors of metabolism (IEM) affect very small numbers of individuals. The entire population, however, of patients suffering the results of inherited metabolic disorders is large, and has been of increasing concern to patient groups and health care professionals in the United States as well as other countries throughout the world. The 1983 US Orphan Drug Act (ODA) serves to facilitate the development of drugs to treat rare diseases by providing several economic incentives. The sponsor of a product designated as an orphan by the Food & Drugs Administration (FDA) Office of Orphan Products Development (OPD) qualifies for tax credits on clinical trial expenses, the award of grant funding by FDA, through the OPD, and 7 years of marketing exclusivity for a designated drug, or biological product that receives FDA market approval. Orphan drug legislation in the US has benefited victims of IEM by encouraging development of drugs for metabolic deficiencies affecting populations that otherwise would be ignored. America's solution to the orphan drug problem has had worldwide impact. The success of this legislation was a factor leading to the 1993 orphan drug law in Japan; the 1997 implementation of a process whereby most FDA-approved orphan drugs and biological products will be similarly approved in Australia; and, in 1999, regulation on orphan medicinal products in the European Union (EU). Today, international support for rare disease research is providing stimulus and motivation to overcome the financial barriers and encourage development of treatment for very rare diseases throughout the world.
Full reference of the article: Haffner ME.FDA Office of Orphan Products Development, Food and Drug Administration, Rockville, MD 20857, USA. "Developing treatments for inborn errors: incentives available to the clinician." Molecular genetics and metabolism, April 2004.
