Ehlers-Danlos Syndrome & the Zebras

“When you hear the sound of hooves, think horses, not zebras.”

This is what medical students are taught.

In the medical field, the term "zebra" is used to describe rare diseases or conditions. To avoid misdiagnosing patients with rare illnesses, doctors are trained to assume that the simplest explanation is usually correct. However, this can make it more difficult for those with rare conditions to receive a diagnosis and treatment.

Ehlers-Danlos Syndromes are generally considered rare, and those who live with EDS are referred to as medical zebras. (Though information gained over the last few years has shown that Hypermobile Ehlers-Danlos Syndrome is more common than once thought. The saying "not so much rare as rarely diagnosed" has been used.)

"What is Ehlers-Danlos Syndrome?"

Ehlers-Danlos Syndrome is a group of 13 inherited disorders that affect the formation and function of your connective tissues, primarily your skin, joints, and blood vessel walls. It affects virtually every organ system.

Connective tissue is a complex mixture of proteins, such as collagen, and other substances that provide strength and elasticity to the underlying structures in your body. It affects virtually every organ system, which can result in significant morbidity and mortality. Severe complications of this disease can include arterial rupture and organ rupture, though these complications are typically only seen in Vascular Ehlers-Danlos Syndrome (vEDS).

Some EDS features are seen across all types of Ehlers-Danlos Syndrome, including joint hypermobility, tissue fragility, widespread chronic pain, and gastrointestinal diseases. The current classification includes 13 types of Ehlers-Danlos Syndrome, and each type has its own genetic causes. This results in a unique set of features for each type of EDS.

"What are connective tissue and collagen?"

Connective tissue is found throughout the body, where it provides support, protection, and structure to other parts of the body. Connective tissue disorders are caused by issues that prevent connective tissue from functioning properly.

Collagen is the primary component of connective tissue. There are different types of collagens with different functions. The Ehlers-Danlos Syndromes are caused by changes in the genes that affect the structure and function of collagen and related connective tissue.

Ehlers-Danlos Syndrome can affect any connective tissue in your body, including your:

• Cartilage

• Bones

• Blood

• Fat

• Organs

Depending on where EDS affects your connective tissue, you might experience symptoms in your:

• Skin

• Tendons

• Joints

• Muscles

• Blood Vessels

  
  

"How common is Ehlers-Danlos Syndrome?"

Experts estimate that 1 in 5,000 people has Ehlers-Danlos Syndrome.

Each type of EDS has a different prevalence in the population. Hypermobile EDS (hEDS) is the most common type of EDS by far. hEDS accounts for about 90% of EDS cases and is thought to affect at least 1 in 3,100-5,000 people. Classical EDS (cEDS) and vascular EDS (vEDS) are much rarer than hEDS. cEDS affects roughly 1 in 20,000-40,000 people. vEDS affects about 1 in 100,000-200,000 people. All other types of EDS are classified as ultra-rare, affecting less than 1 in 1 million people. Each type of EDS is caused by variants in specific genes that provide the instructions for making collagens and related proteins. Some types of EDS are associated with multiple genes. Unfortunately, the genetic cause(s) of hEDS have not been identified.

"What are the signs you may have EDS?"

Because each type has its distinct features, it is a hard question to answer. As noted above, there are a few symptoms that can be found in all types of Ehlers-Danlos Syndrome, and three of those are Hypermobility, Skin Fragility, and Skin Hyperextensibility. Many people with EDS deal with chronic dislocations and/or subluxations. You will often find comorbid conditions like autonomic dysfunction, G.I. diseases, mast cell diseases, craniocervical instability, and chronic migraines in people with EDS/HSD. If you think you may have Ehlers-Danlos Syndrome, or Hypermobility Spectrum Disorder (HSD), do not hesitate to advocate for yourself with your doctors.

Our favorite (American) resource for Ehlers-Danlos Syndrome is the Ehlers-Danlos Society.

Sources: Mayo Clinic, Cleveland Clinic, NIH, and The Ehlers-Danlos Society.