Ehlers-danlos syndrome is a group of heritable connective tissue disorders. This condition affects the connective tissues that support the blood vessels, bones, skin and various other organs of the body. There are six types of this syndrome which presents very specific features. They are the classical type, hypermobility type, the vascular type, the kyphoscoliosis type, the arthrochalasia type and the dermatosparaxis type. Although all the types of this syndrome affect the joints and the skin, the additional features associated with this condition vary. However, some of the symptoms that all the types share include the increased range of joint movement (joint hypermobility), stretchy skin and fragile skin that bruises easily. The combined prevalence of all the types of this syndrome is estimated to affect around 1 in 5,000 individuals globally.
Causes
The classical type is the result of a mutation in the gene COL5A1 or the COL5A2 and a small percentage of mutation in the TNXB gene causes hypermobility type. The vascular type is the result of a mutation in COL3A1 and PLOD1 mutation causes the kyphoscoliosis. The genetic mutation in the gene COL1A1 or COL1A2 causes arthrochalasia and mutation in the ADAMTS2 cause dermatosparaxis.
Some of these genes are responsible for producing the units of different types of collagen which assemble together to give structure to the connective tissues throughout the body. The various genetic mutations affect the production or the processing of collagen which consequently weakens the connective tissues of the skin, bones and other parts of the body. The arthrochalasia, classical, hypermobility and vascular forms of this syndrome are inherited in an autosomal dominant pattern meaning one copy of the defective gene is sufficient to cause this disorder. The dermatosparaxis and kyphoscoliosis types are inherited in an autosomal recessive pattern where both the copies of the gene in each cell are defective.
Symptoms
The common features of this syndrome affect the joint and the skin. The abnormalities of the joints include loose or unstable joints which can dislocate, early onset of osteoarthritis and hypermobility. The skin problems can include soft fragile skin that tears or bruises easily, poor wound healing and fleshy lesions. The symptoms of hypermobile type include joint pain, fatigue, digestive problems, internal organs issues such as organ prolapse and problems with bladder control. The classical type presents hernias, organ prolapse and skin problems. The vascular type is a rare type featuring fragile blood vessels with the risk of internal bleeding, unusual facial features such as thin nose and organ problems such as bowel or the womb tearing. The kyphoscoliotic type is characterized by a curvature of the spine, weak muscle tone (hypotonia) and fragile eyes.
Diagnosis
Generally, the diagnosis is assessed based on the features of each type, evaluating the patient and their family history along with various diagnostic tests. In some cases, the test may involve a skin biopsy which is observed under the microscope to detect the collagen structure abnormality. In addition, various specialized tests can include a CT scan, MRI and echocardiography that can identify features such as aortic dilatation. Genetic testing is available for most of the types of this syndrome except the common type hypermobility.
Treatment
The treatment is based on the various symptoms that are evident in each type of this syndrome. These cases may require special braces to stabilize affected joints along with various therapeutic techniques to strengthen the muscles and to preserve the joints. Female patients with the vascular type of this syndrome should be counseled on the complications that can develop during pregnancy. Genetic counseling may be beneficial for some of the affected individuals and their family.
References
https://rarediseases.org/rare-diseases/ehlers-danlos-syndrome/
http://ehlers-danlos.com/what-is-eds/
https://ghr.nlm.nih.gov/condition/ehlers-danlos-syndrome#inheritance
http://www.nhs.uk/Conditions/ehlers-danlos-syndrome/Pages/Introduction.aspx
