Deep Dive

Basics to Know If You're Newly Diagnosed or Know Someone Who Is

When was hypermobility discovered?

In 1892, the Russian dermatologist Dr. Tschernogubow published the first comprehensive description of hypermobility, according to this NIH EDS research report. The syndrome derives its name from additional clinical case reports presented by two physicians: Edvard Ehlers, in 1901, recognized the condition as a distinct entity. In 1908, Henri-Alexandre Danlos suggested that skin extensibility and fragility were the cardinal features of the syndrome and it was named after them. But Hippocrates was enamored with it 1,000 years before in 400 BC when he noticed there was a distinct group of people presenting with bruising and blood disorders. So, it’s not new! But doctors still don’t understand it or know how to recognize it in patients.

To understand the basics, first we address the most common type of EDS – the hypermobile type. Hypermobile EDS (hEDS), and Hypermobility Syndrome Disorder (HSD) are on a spectrum of varying degrees of severity depending on the individual and the areas of the body they affect. Hypermobile EDS is only one type of EDS, but is becoming known as “the most common disorder you’ve never heard of” theorized by Dr. Chip Norris at the MUSC Norris Lab studying the disorder.

Overview

Here’s a brief explanation:

hEDS
A genetic connective tissue disorder that can be inherited or caused by a new mutation. To be diagnosed with hEDS, a patient must meet three criteria: have generalized joint hypermobility (GJH), have features of inherited connective tissue disorders, and not meet the criteria for other disorders with similar symptoms. Other features of hEDS include skin hyperextensibility, fragile tissues, and joint instability.

HSD
A group of disorders that involve joint hypermobility without other significant connective tissue abnormalities. To be diagnosed with HSD, a patient must have symptomatic joint hypermobility but not meet the criteria for hEDS or other similar conditions. HSD is further divided into four subtypes based on which joints are involved, whether the hypermobility is generalized, and if other musculoskeletal problems are present.

To learn more about the differences and similarities between hEDS and HSD, read this comparison.

What are the Ehlers-Danlos syndromes?

The Ehlers-Danlos syndromes (EDS) are a group of thirteen (some say fourteen) individual genetic conditions, all of which affect the body’s connective tissue. Connective tissue lies between other tissues and organs, keeping these separate while connecting them, holding everything in place, and providing support, like the glue between your bones. It affects women more than men and causes symptoms in multiple organs. Therefore, it requires multiple disciplinary care teams and specialists who focus on separate body systems.

In EDS, a gene mutation causes a certain kind of connective tissue – the variety will depend on the type of EDS but usually a form of collagen – to be fragile and stretchy. This stretchiness can sometimes be seen in the skin of someone with EDS; individuals with the condition may also be able to extend their joints further than is usual – this is known as being hypermobile, bendy, or double-jointed. As collagen is present throughout the body, people with EDS tend to experience a broad range of symptoms that are less visible than the skin and joint differences. These are complex syndromes affecting many systems of the body at once. Despite this, EDS is often an invisible disability. Symptoms commonly include, but are not limited to, long-term pain, chronic fatigue, dizziness, palpitations, and digestive disorders. Such problems and their severity vary considerably from person to person, even in the same type of EDS and within the same family.

Where Does It Come From?

The Ehlers-Danlos syndromes are a group of genetically inherited connective tissue disorders which are currently classified in a system of the various types as described above. Despite this grouping and their common name, each type is a distinct condition caused by a different gene mutation. This means that a child cannot inherit a different kind of EDS from the one their parent has. It also means that one type cannot later turn into another, and there is no increased risk of having another type just because you have one. There is a 50% chance you pass the hereditary condition to your children.

What’s in a Label?

Some of the criteria used to diagnose the Ehlers-Danlos syndromes and some of the terminology describing them have changed over time to reflect scientific research from the past twenty years to current day. The only classification system that exists to date, known as The 2017 EDS International Classification Diagnostic Criterion that first outlined thirteen types of EDS and defined for the first time some related conditions, the hypermobility spectrum disorders (HSD), which have similar symptoms to hypermobile EDS (hEDS). The term joint hypermobility syndrome (JHS)  or "type 3" is no longer used.

The most common type of EDS is thought to be the hypermobile type (formerly known as the hypermobility type or type 3). However, the exact prevalence of this condition is not currently known. The medical literature currently states that it affects 1 in 5,000 people; however, this statistic is based on very out-of-date research, and hEDS/HSD frequently go undiagnosed or are misdiagnosed as other conditions. HSD and possibly hEDS are likely to be much more common. The MUSC Norris Lab studying hEDS believe it could be as common as 1 in every 500. The classical and vascular types are rare, with different types still rarer. All the classes are probably underdiagnosed to some degree. The gene mutations causing the rarer types have been identified. They can be tested in all types except for the most common type, hypermobile EDS.

Understanding the Various Types

What’s at the heart of the issue in EDS? Collagen