Heather A. Lau, MD, Director, Lysosomal Storage Disease Program at NYU Langone in New York City discusses how physicians need to consider rare diseases for some of their more challenging diagnositic cases.

Rare diseases are problematic on many fronts: (1) providers need to keep in mind the many ambiguous clinical signs that lead to a diagnosis of a specific disease; (2) providers then need to recognize these signs in their practice settings—something that is difficult unless they are looking for them; (3) then there is the challenge of coming up with a proper diagnostic work-up and translating those reports into a diagnosis.

According to Global Genes, a leading rare disease patient advocacy organization, it takes an average of 7.6 years in the United States and 5.6 years in the United Kingdom for a patient with a rare disease to receive a correct diagnosis. During this time, the average patient will be misdiagnosed two or three times while visiting four primary care physicians and four specialists. Since it is estimated that more than 25 million Americans have what is considered a rare disease, it is well understood that there are many patients suffering from rare diseases who go undiagnosed and are seeking a clinician to assist in matching their unique symptoms to a specific rare disease.

Although physicians may not consider rare diseases in their daily practices, it is likely that most clinicians encounter patients suffering from these disorders on a somewhat regular basis. Because there are approximately 7000 rare diseases, it is unrealistic to expect clinicians to know exactly which symptoms are unique to a rare condition compared with those that are more likely due to a common ailment. The Rare Disease Community usually offers the following advice for doctors when presented with a patient with a challenging or difficult case to diagnose:

  1. Refer your patients to a specialist or to a physician with more experience with rare diseases.
  2. Listen to your patients and their caregivers. It is often said that patients are the experts in their rare disease and as information has become readily available on-line, many patients and caregivers have begun to educate doctors on the possibility of a rare condition. That, along with the increased number of orphan drugs available, well-organized patient advocacy groups, and better search engines, has helped increase awareness of rare diseases.

Sometimes diagnosing a rare disease can be like finding a needle in a haystack. A common narrative shared in the rare disease community is that physicians are taught in medical school to think in general terms, ie if ranchers hear hoof beats, they assume that a horse is behind them and not a zebra. In most cases, when clinicians see a series of symptoms, they assume they are related to a common ailment, not a rare one. In many cases, the provider will be right in making that assumption, but after a second or third test comes back inconclusive, it is in the physician’s and patient’s best interest to assume those hoof beats may belong to something other than a horse. (Taking the Steps to Improve Early Diagnosis of Rare Diseases  http://www.futureofpersonalhealth.com/prevention-and-treatment/taking-the-steps-to-improve-early-diagnosis-of-rare-diseases Accessed July 11, 2018.)