Rare Diseases

Key Points

  • In the United States, a disease is considered a rare disease or a rare disorder if it affects fewer than 200,000 people.
  • The NORD® Rare Disease Database contains over 10,000 rare diseases.
  • Each disease may be rare individually, but people with rare diseases often experience similar challenges. These challenges may include accessing information, getting a diagnosis, and finding resources.

What Are Genetic Diseases or Conditions

Genetic diseases or conditions are those caused by an error or mutation (change) in a person’s DNA. These mutations can cause proteins to be built incorrectly, leading to changes in how the body functions and resulting in symptoms of a rare disease.

Rare Diseases Are More Common Than You Think

Rare diseases are more common than you’d expect and are estimated to affect more than 30 million people in the U.S. This means that 1 in 10 people in the U.S. have a rare disease.

In Washington, between 700,000 and 800,000 people may have a rare disease. Those living with rare diseases often have a long journey to get a diagnosis before they can start managing their condition.

Rare Diseases Are a Public Health Concern

Many rare diseases are genetic, and about 80% have a genetic cause. Some are noticeable at birth, while others develop later during a person’s life. About two-thirds of people in the U.S. with rare diseases are children.

Symptoms Can Vary Widely

Rare disease symptoms and their effects on patients are as diverse as the diseases themselves. Symptoms can:

  • Appear at any time during a person’s life -- childhood, adulthood, or both.
  • Affect single or multiple parts of the body.
  • Be different even among people with the same condition.

Treatment and Diagnosis Challenges

Of the 7,000 known rare diseases, approximately 95% have no treatment options. It can take years to receive an accurate diagnosis due to little or no research on many rare diseases. Other challenges include:

  • Difficulty finding physicians or treatment centers experienced in rare diseases.
  • High treatment costs, often not covered by insurance.
  • Reimbursement issues related to private insurance, Medicare, and Medicaid.
  • Isolation experienced by patients and caregivers due to fewer support networks.
  • Challenges getting medical, social, or financial services or assistance because decision-makers may not be familiar with a disease.

Resources and Support

If you suspect you have a rare disease or care for someone with a rare disease, use the trusted resources below to learn more.

Washington-Based Resources

  • NW Rare Disease Coalition
    Support for the Pacific Northwest's rare disease community.
  • Pacific Northwest Undiagnosed Disease Network
    Assistance for patients with rare or difficult-to-diagnose conditions. This network is part of the National Institutes of Health (NIH) Undiagnosed Diseases Network and based at the University of Washington and Seattle Children’s.
  • GREGoR Consortium
    Approaches to discover the cause of currently unexplained rare genetic disorders.
  • University of Washington Center for Rare Disease Research
    One of the leading centers working to identify the genetic basis of Mendelian conditions for which the underlying cause is unknown.
  • Rare Diseases Inclusion and Exclusion Criteria (PDF)
    This document outlines the process we used to select the 126 rare diseases in the Rare Disease resource created by the Washington State Department of Health. Below is an overview of our process:
    • First, we used 2 AI tools to list the 100 most “common” rare diseases. We then added 10 more diseases identified through professional organizations and other sources.
    • Next, we applied criteria to optimize our list. We focused on including more diseases by expanding on specific categories of conditions. We excluded diseases that were adult-onset, duplicates, combined conditions or did not meet the definition of rare as determined for this resource (prevalence of 1 in 1,000 to 1 in 250,000). This process gave us a list of 114 diseases.
    • We then included conditions screened in Washington as part of the prenatal carrier screening, newborn screening, and those recommended by national guidelines from the Recommended Uniform Screening Panel as of June 2024. This step added 12 more diseases.
    • Some of these conditions did not meet this resource’s criteria for rare, but they were included since WA DOH screens or recommends screening for them.
    • The final resource includes information on 126 rare diseases.

National Resources

For Community

For Providers and Health Care Professionals

International Resources