Mary Ellen Motyl

Unlocking the Hidden Links: Similarities Among Rare Diseases?

Unlocking the Hidden Links: Similarities Among Rare Diseases?

The criteria for what constitutes a rare disease differs from one country to another. For instance, the FDA Orphan Drug Act defines a rare disease as one that affects fewer than 200,000 people in the United States1. In the European Union, a rare disease is defined as one that affects no more than one person in 2,0002. Japan’s legal definition considers a disease rare if it affects fewer than 50,000 or about 1 in 2,500 people3. Given the lack of a universal definition, it raises the question: Could there be any similarities among rare diseases?

Rare diseases, by their very nature, are characterized by their uncommonness and heterogeneity, with each exhibiting a distinct set of symptoms and unique etiology. Even among patients with the same disease, presentations can differ. However, after conducting multiple landscape and patient journey market research studies across various rare diseases, several similarities emerge. While patients’ disease experiences may be unique, they collectively share similar narratives when it comes to diagnosis and treatment.


Although the precise origin of many rare diseases is unknown, the majority are believed to be caused by mutations in genes that manifest during childhood with devastating consequences. The genetic mutations are often passed from one generation to another, though sometimes, they might only affect a single person or occur spontaneously. Other factors considered to play a role are environmental in nature – chemical exposure, smoking, or diet.


The rarity of these conditions, their array of seemingly unrelated symptoms that often mimic other more common diseases, and the limited awareness of healthcare professionals contribute to the challenge of diagnosing rare disease patients.

In addition, there is a lack of diagnostic criteria and resources for physicians to access when considering diagnostic possibilities. The lack of condition-specific codes adds to healthcare professionals' ability to record and create meaningful databases for each rare disease.

The majority of patients will seek the expertise of up to eight healthcare professionals, undergo extensive testing across various medical facilities, and receive multiple incorrect diagnoses before finally receiving an accurate differential diagnosis. Often, these patients are misdiagnosed as having a mental health condition.

The average time for a rare disease to be diagnosed ranges from four to ten years; some patients die without a correct diagnosis.

Challenges with Coordination of Care

Patients often seek out specialized centers traveling long distances to consult with and receive care from the few experts with experience in treating their rare disease. Some families even relocate to have access to these specialists.

The complex nature of rare diseases, often coupled with multiple organ involvement, necessitates specialists to address the various aspects of the disease. Geneticists, neurologists, endocrinologists, physiotherapists, dieticians, and other specialists are usually involved in treating rare diseases. This multispecialty involvement often presents communication challenges between specialties, resulting in poorly coordinated care.

Limited Treatment Options

Most rare diseases lack any specific targeted therapies. The complex biology, lack of understanding of the underlying causes, and low prevalence of a rare disease hinder treatment research and drug development. In addition, the small patient population makes it less economically viable for pharmaceutical companies to invest in treatment research. The potential for a return on investment for therapies is limited.

Due to limited clinical research, most treatments for rare diseases aim to treat symptoms and/or prevent complications. There are some disease-modifying therapies, though many are short-lived and require the treatment to be repeated indefinitely. Curative therapies for rare diseases are in and of themselves rare.

Family and Emotional Impact

The impact of coping with uncertainty, managing symptoms, and adjusting to changes in lifestyle can be challenging. This physical and emotional isolation that patients experience affects their mental well-being. Families and caregivers often face significant challenges in providing support and managing the complexities of the disease. Learning new, highly specialized medical terminology and trying to understand their disease can be daunting.

Many rare diseases lack any support groups or resources to help. As a result, patients with rare diseases often become advocates for research, as there may be limited data on their condition. They might participate in clinical trials to help advance knowledge and potential treatments, attend conferences, and create social media spaces to share what they’ve learned.

Financial Toxicity

Patients and their families with rare diseases often experience significant financial toxicity.

Their search for a diagnosis is often not only time-consuming but costly. The prolonged time to diagnosis involves numerous tests and consultations with specialists. Once a diagnosis is confirmed, costs associated with the ongoing care of rare diseases can be substantial, especially if specialized treatment, medications, or assistive devices are needed. Travel to access specialized care, participate in clinical trials, or seek expert opinions leads to transportation, lodging, and food expenses. Insurance coverage might be limited, leading to high out-of-pocket costs, and patients may need to navigate complex reimbursement processes.

Many of these patients or their caregivers are unable to work or require frequent absences, resulting in a loss of income.

While rare diseases can vary significantly based on the specific disease, its symptoms, availability of treatments, and the level of medical and social support, there are multiple commonalities and challenges that tend to emerge across rare diseases. Recognizing these similarities among rare diseases can lead to deeper insights and more in-depth analysis when conducting market research, ultimately benefiting both our clients and patients.

Clock on the following Read More link to access a summarizing infographic:



1 “Rare Diseases at FDA,” U.S. Food & Drug Administration, https://www.fda.gov/patients/rare-diseases-fda#:~:text=The%20Orphan%20Drug%20Act%20defines,people%20in%20the%20United%20States

2 “Rare Diseases,” European Commission Research and Innovationhttps://research-and-innovation.ec.europa.eu/research-area/health/rare-diseases_en#:~:text=EU%20research%20on%20rare%20diseases,million%20people%20in%20the%20EU

3  “Rare Diseases: what are we talking about?” Rare disease centre-Venetian Region – Italy. Retrieved 21 January 2022.            

About the Author:

Mary Ellen Motyl, Moderator

Mary Ellen is a RIVA-trained moderator focused on medical and pharmaceutical clients. She has worked on projects ranging from exploratory and unmet needs, to positioning, and concept development and more using a variety of methodologies. She has seamlessly coordinated complex projects ranging from multi country studies to mixed physician and patient focus groups. Mary Ellen holds a BS in Business Management from Northern Illinois University.

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