What is a medical zebra?

A medical zebra is rare a disease, one that is so rare that most doctors have not encountered a patient with that disease. Having only read about the disease in a textbook or in the case of many recently defined diseases, not at all. It is therefore difficult for medical doctors to diagnose these individuals. The term originates from a popular saying among clinicians, "when you hear hoofbeats, think horses, not zebras", meaning that when diagnosing a patient, one should first exclude the most common causes for a patients symptoms, before looking for rare causes. While this is a good idea in everyday practice, one must not forget to make the effort to go "zebra hunting" when the common causes don't explain the full clinical picture. This is especially important with the current growth of genetics and personalised medicine.

A medical zebra may also refer to a patient with an unusual presentation of a common disease, making it difficult to diagnose the patient. This is especially true for patients with multiple diseases, where the symptoms of one disease may mask the symptoms of another.

Did you know?
About 80% of rare diseases have a genetic origin, and about 1 in 17 people will be affected by a rare disease at some point in their life.
Source: Eurordis

Medical Zebras is a website about medicine, genetics and pathology.
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The information provided is for educational purposes only and does not constitute medical advice.