The arthrochalasia type of Ehlers-Danlos syndrome (EDS Types VIIA or VIIB) is associated with defects in the amino-terminal ends in procollagen Type I chains that can result in weakening of collagen in connective tissues. Athrochalasia indicates severe and abnormal flaccidity of the joints. The diagnosis can be confirmed by laboratory testing.


Inheritance: autosomal dominant


Biochemical Defect: Deficient processing of the amino-terminal end of chains of collagen type I because of skipping of exon 6. In Type VIIA the pro-alpha1(I) chains are affected; in Type VIIB the pro-alpha2(I) chains are affected.


Major criteria:

(1) severe generalized joint hypermobility with recurrent subluxations

(2) congenital bilateral hip dislocations


Minor criteria:

(1) skin hyperextensibility

(2) tissue fragility with atrophic scars

(3) easy bruisability

(4) muscle hypotonia

(5) kyphoscoliosis

(6) mild osteopenia


Laboratory confirmation:

(1) electrophoresis of procollagen chains extracted from dermal fibroblasts

(2) demonstration of exon 6 skipping in cDNAs of COL1A1 or COL1A2


Distinction from EDS Type VI requires biochemical analysis.


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