Collagen genetic types

The many (possibly more than 30) types of collagens found in human connective tissues have substantially the same chemical structure consisting mainly of glycine with smaller amounts of proline and some lysine and alanine. In addition, there are two unusual amino acids, hydroxyproline and hydroxylysine, neither of which has a corresponding base-triplet or codon within the genetic code. There is therefore, extensive post-translational modification of the protein by hydroxylation and also by glycosylation reactions. 

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. 

Bachinger HP, Morris NP, Davis JM Thermal stability and folding of the collagen triple helix and the effects of mutations in osteogenesis imperfecta on the triple helix of type I collagen., 1/ / J Med Genet 45 152-162,1993. 

Schwatze U, Starman BJ, Byers PH (1999) Redefinition of exon 7 in the COLlAl gene of type I collagen by an intron 8 spUce-donor-site mutation in a form of osteogenesis imperfecta influence of intron splice order on outcome of splice-site mutation. Am J Hum Genet 65 336-344... 

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