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What is a Rare Disease?

February 23, 2021

In the United States, rare diseases affect fewer than 200,000 people, according to the Orphan Drug Act of 1983. Combined, all rare diseases, sometimes referred to as “orphan diseases,” are one of the most common groups of diseases in the U.S. In fact, 1 in 10 Americans is affected by a rare disease.

While each rare disease is uncommon in frequency, collectively there are about 7,000 rare diseases, according to the National Organization for Rare Disorders (NORD). By visiting the NORD website, you can get information on 64 categories of rare diseases.

Some diseases listed vary in frequency from rare to ultrarare, affecting as few as 100 people to as many as several thousand people in the U.S. The National Center for Advancing Translational Science (NCATS) suggests this number is up to 7,000 per disease. Rare diseases collectively affect 25-30 million Americans. Based on the 2019 U.S. population estimate of 328.2 million, rare diseases affect 8-9% of Americans.

About rare diseases

  • Rare diseases can be challenging for your healthcare providers for many reasons. This is true not only because they are rare but also because their symptoms can vary. These key factors make most doctors unfamiliar with these conditions. This often leads to delays in diagnosis, which impacts early treatment intervention.

    For accurate diagnosis and treatment, rare diseases should be evaluated by specialists at large academic medical centers, such as The University of Kansas Health System. In neurosciences alone, rare diseases include amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), Guillain-Barre syndrome (GBS), chronic inflammatory demyelinating polyneuropathy (CIDP), muscular dystrophies, myositis, myasthenia gravis, Pompe disease, Fabry disease, hereditary transthyretin amyloidosis and others.

  • While some rare diseases are due to rare infections, rare cancers or some autoimmune diseases, most are genetic or inherited in nature. Genetic or inherited diseases are due to a variety of changes in the human genes. As with other inherited traits, disease transmission can be dominant, recessive or X-linked.

  • The diagnostic journey can last for years. At large academic centers, such as ours, specialists in heart, liver, neurologic system, kidney and genetics care – among others – often establish the diagnosis. A correct diagnosis can be a relief for patients and their loved ones. But it is also the beginning of creating the best treatment plan for each patient.

  • After a diagnosis is made, the focus shifts from knowing the cause of the disease to developing an appropriate and customized care plan including available treatment, care coordination and opportunities to participate in clinical research. Regardless of the specific rare disease, patients benefit from coordinated care from specialists who come from many disciplines and work together as one team to address all aspects of a patient’s care.

    At The University of Kansas Health System and University of Kansas Medical Center, someone with ALS, for example, will work with a care team consisting of the doctor, doctor-in-training, clinical nurse, physical therapist, occupational therapist, respiratory therapist, nutritionist, social worker, adaptive and respiratory device representative, patient advocacy group representative and research coordinator.

    In addition to supportive care, some people with rare diseases benefit from FDA-approved, targeted, novel therapies.

  • Research studies are ongoing in many rare diseases. This work is done to improve on currently approved treatments and to discover new treatments where none are available. These studies not only offer hope to people with rare diseases but make early diagnosis even more critically important.

  • It still holds true that management of many of rare diseases is limited to supportive care. However, this is evolving. Exciting advances in treating rare diseases can result from our improved understanding of gene therapies.

What is the main thing people should know if they have a rare disease?

People with rare diseases benefit most from an early diagnosis. This is best done at large academic medical centers such as The University of Kansas Health System. In addition to the most advanced supportive care, we offer targeted therapies for people with rare disease.

We offer patients the opportunity to learn about ongoing research through our strong partnership with the University of Kansas Medical Center. This also allows patients to help drive the future of research and to participate in studies of their choosing. Another benefit is our partnerships and collaboration with patient advocacy groups that champion education, care and research for people with rare diseases.

Doctors and nurses collaborating

Leading research and clinical trials

As part of one of the nation's premier academic medical centers, our care providers are committed to research and scientific discovery through the University of Kansas Medical Center. We can often include our patients in potentially lifesaving clinical trials and treatment options not available anywhere else.

Our Research

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