Ehlers–Danlos syndromes (EDS) are a group of 13 genetic connective-tissue disorders in the current classification, with the latest type discovered in 2018. Symptoms often include loose joints, joint pain, stretchy velvety skin, and abnormal scar formation. These may be noticed at birth or in early childhood. Complications may include aortic dissection, joint dislocations, scoliosis, chronic pain, or early osteoarthritis.

EDS occurs due to variations of more than 19 genes that are present at birth. The specific gene affected determines the type of EDS. Some cases result from a new variation occurring during early development, while others are inherited in an autosomal dominant or recessive manner. Typically, these variations result in defects in the structure or processing of the protein collagen.

Diagnosis is often based on symptoms and confirmed by genetic testing or skin biopsy, but people may initially be misdiagnosed with hypochondriasis, depression, or chronic fatigue syndrome.

A cure is not yet known and treatment is supportive in nature. Physical therapy and bracing may help strengthen muscles and support joints. Some forms of EDS result in a normal life expectancy, but those that affect blood vessels generally decrease it.

The hypermobile type of EDS (hEDS) affects at least one in 5,000 people globally; other types occur at lower frequencies. The prognosis depends on the specific disorder. Excess mobility was first described by Hippocrates in 400 BC. The syndromes are named after two physicians, Edvard Ehlers and Henri-Alexandre Danlos, who described them at the turn of the 20th century.