Collagen genetic defects

Any major protein of the body is likely to be associated with a number of genetic problems. In the case of collagen, the possibility for harmful mutations is enhanced by the existence of a large number of genes that encode the more than 16 types of collagen which are expressed differently in different tissues. There are known human disorders resulting from defects in synthesis, secretion, or structure of types I,... 

Many epidemiological, clinical, genetic, and biochemical studies have been conducted since the first widely recognized descriptions of OI in the 18th century. The disease has been shown to be caused by defective synthesis of type I collagen, a triple helical protein made from two a 1(1)- and one a2(I)-chains with fibers that form the structural frame of bone matrix. 

Several collagen disorders result from defects in the formation of cross-links (Chapter 11). The cross-linking disorders can be due to a hereditary deficiency of lysyl oxidase, inhibition of lysyl oxidase, deficiency of copper, defects in the formation of cross-links, or defects in their stabilization. The genetic deficiency of lysyl oxidase is characterized by Ehlers-Danlos syndrome type IX (Table 25-5) and some forms of cutis laxa. Type IX Ehlers-Danlos syndrome patients exhibit extreme extensibility of the skin, cigarette-paper scarring, and easy bruisability. In cutis laxa, the skin is loose and inelastic and appears to be too large for the surface it covers. Some affected individuals exhibit deficiency of lysyl oxidase, presumably... 

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