Inheritance is usually autosomal dominant, but Ehlers-Danlos syndrome is heterogeneous. Different gene mutations affect the amount, structure, or assembly of different collagens. Mutations can exist in the genes that encode collagens (eg, type I, III, or V) or collagen-modifying enzymes (eg, lysyl hydroxylase, a collagen-cleaving protease).
There are 6 major types:
There are also several rare or hard-to-classify types.
Symptoms and signs of Ehlers-Danlos syndrome vary widely.
Predominant symptoms include hypermobile joints, abnormal scar formation and wound healing, fragile vessels, and velvety, hyperextensible skin. Skin can be stretched several centimeters but returns to normal when released.
Wide papyraceous scars often overlie bony prominences, particularly elbows, knees, and shins; scarring is less severe in the hypermobility type. Molluscoid pseudotumors (fleshy outgrowths) frequently form on top of scars or at pressure points.
Extent of joint hypermobility varies but may be marked in the arthrochalasis, classic, and hypermobility types.
Bleeding tendency is rare, although the vascular type is characterized by vascular rupture and bruising. Subcutaneous calcified spherules may be palpated or seen on x-rays.
Minor trauma may cause wide gaping wounds but little bleeding; surgical wound closure may be difficult because sutures tend to tear out of the fragile tissue. Surgical complications occur because of deep tissue fragility. Sclera may be fragile, leading to perforation of the globe in the kyphoscoliosis type.
Bland synovial effusions, sprains, and dislocations occur frequently. Spinal kyphoscoliosis occurs in 25% of patients (especially in those with the kyphoscoliosis type), thoracic deformity in 20%, and talipes equinovarus in 5%. About 90% of affected adults have pes planus (flat feet). Developmental dysplasia of the hip (formerly congenital hip dislocation) occurs in 1% (the arthrochalasis type is characterized by bilateral developmental dysplasia of the hip).
Gastrointestinal (GI) hernias and diverticula are common. Rarely, portions of the GI tract spontaneously hemorrhage and perforate, and dissecting aortic aneurysm and large arteries spontaneously rupture.
Valvular prolapse is a common complication in the most severe type (vascular type).
In pregnant women, tissue extensibility may cause premature birth, cervical incompetence, and possibly uterine rupture; if the fetus is affected, fetal membrane is fragile, sometimes resulting in early rupture. Maternal tissue fragility may complicate episiotomy or cesarean delivery. Antenatal, perinatal, and postnatal bleeding may occur.
Other potentially serious complications include arteriovenous fistula, ruptured viscus, and pneumothorax or pneumohemothorax.
Initial diagnosis of Ehlers-Danlos syndrome is largely clinical but should be confirmed by genetic testing, which is now available for most subtypes. Ultrastructural examination of skin biopsy can help in diagnosing the classic, hypermobility, and vascular types.
Echocardiography and other vascular imaging are done to check for heart disorders (eg, valvular prolapse, arterial aneurysm) that are associated with some of the types.
There is no specific treatment for Ehlers-Danlos syndrome. Trauma should be minimized. Protective clothing and padding may help. If surgery is done, hemostasis must be meticulous. Wounds are carefully sutured, and tissue tension is avoided.
Obstetric supervision during pregnancy and delivery is mandatory. Genetic counseling should be provided.