Ehlers Danlos Syndrome (EDS) is a genetic disease, although many people start having symptoms very late in their lives. People with EDS produce faulty collagen. Collagen is everywhere in the body and depending on the type of collagen affected, the symptoms can vary.
There are 7 recognised types of EDS and by far the most common one is EDS 3 also called Hypermobility EDS (HEDS).
Coccyx subluxations are relatively common in HEDS patients (not formal statistics, but by reading forums I would say that 15-20% of HEDS patients has experienced serious coccyx problems) which is why it is important that this illness is understood by anyone with coccyx issues.
In Hypermobility EDS the collagen defects impact tendons and ligaments, allowing for an unusually high range of motion in joints. Something that has been described for a long time as being "double jointed". Children with HEDS do "party tricks" to impress their friends and adults tend to be much more flexible than the average population.
The symptoms may vary widely, from mild hypermobility to very serious cases where over the years joints get progressively damaged through recurrent subluxations and dislocations leading to disability. HEDS often includes other symptoms driven by collagen weakness: mildly stretchy skin, GERD and IBS, gastroparesis, dysautonomia/postural orthostatic tachycardia (POTS) and frequent allergies/mast cells activation syndrome.
In many instances people affected by HEDS are not aware of having the condition, which is significantly underdiagnosed. They might have a medical history of "incidents" or recurrent problems with sports but no one has "connected the dots". Also, symptoms of HEDS sometimes are really minor until an event (puberty, menopause, trauma, surgery) triggers a sudden deterioration of the condition.
HEDS is diagnosed through clinical examination only as the gene(s) causing it have not been identified yet. Other forms of EDS can be diagnosed through blood tests or biopsies. The doctor - usually a geneticist, sometimes a rheumatologist - will perform a series of mobility tests (Beighton scale), collect a detailed medical history and a family history.
Unfortunately, no cure has been found yet, but a diagnosis is important in order to understand how to manage the condition through physiotherapy and lifestyle changes. It is particularly important to be aware of interactions with certain medications.