Several mutations in the COL1A2 gene are responsible for
the ‘Arthrochalasia Type’ of Ehlers-Danlos Syndrome (EDS). These mutations,
which affect one copy of the COL1A2 gene
in each cell, delete a segment of the pro-α2 (I) chain that attaches one collagen
molecule to another. The absence of this important segment prevents the normal
assembly of type I collagen fibrils and alters the cross-linking between
collagen molecules. These changes mainly affect tissues that are rich in type I
collagen, such as the skin, bones, and tendons.
Rarely, mutations in both copies of the COL1A2 gene
in each cell have been reported in people with the characteristic features of
Ehlers-Danlos syndrome. These mutations prevent cells from producing any normal
pro-α2 (I) chains. As a result, type I collagen fibrils in the skin and other
tissues cannot be assembled correctly. The presence of abnormal collagen is
associated with a variety of signs and symptoms, including loose joints,
cardiac problems and other complications associated with Ehlers-Danlos
syndrome.
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