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Disease summary:
Ligamentous laxity predisposes to joint instability, subluxations, and dislocations.
Chronic pain and fatigue are common.
The classical type is distinguished from the hypermobility type by the presence of skin fragility, hyperelasticity, and atrophic scarring in the former.
Additional features may include easy bruising, prolonged bleeding, cardiovascular autonomic dysfunction, mild-to-moderate aortic root dilation, and functional bowel disorders.
Hereditary basis:
Both types of EDS are inherited in an autosomal dominant pattern.
The genetic basis of most cases of hypermobility type EDS is unknown.
Mutations in one of the two genes for type V collagen account for half of cases of classical type EDS.
Differential diagnosis:
Four other types of EDS are described in Table 169-1.
There are dozens of other genetic causes for ligamentous laxity, including (but not limited to) Marfan syndrome, Loeys-Dietz syndrome, Stickler syndrome, fragile X syndrome, and Turner syndrome.
Hypotonia, which itself is a feature of many genetic conditions, can also cause joint laxity, and may be difficult to distinguish from ligamentous laxity.
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Diagnostic Criteria and Clinical Characteristics
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Joint laxity is semi objectively measured with the Beighton scale (1 point each for ability to place palms on the floor with knees straight; hyperextension of each elbow or knee >10 degrees; dorsiflexion of each fifth finger >90 degrees; passive apposition of each thumb to flexor surface of forearm). A score of 5 or more is considered positive, but males, older individuals, and those with arthritis and/or history of trauma typically have less laxity, so lower scores may be considered positive.
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Skin elasticity is best measured ...