5 nots - 1 Ehlers-Danlos Syndrome(EDS and Basal...

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1 September 22, 2008 Lecture 5 Ehlers-Danlos Syndrome (EDS) and Basal laminae/Basement Membranes Ehlers-Danlos Syndrome (EDS) is a diverse group of heritable connective tissue disorders. The primary clinical features include soft, hyperextensible skin, scarring, easy bruising and joint hypermobility. Depending on the clinical presentation and molecular basis of the pathology, EDS are classified into six types. The details of the clinical features and genetic defects were presented in the last class. You are not responsible for remembering the clinical features of all the different subtypes of EDS, only the two examples that will be presented in the lecture: classical and dermatosparaxis EDS. Be aware that the list of genetic defects is only representative and that the underlying cause of a particular EDS subtype is genetically heterogeneous. Classical type EDS Classical EDS is often caused by mutations in fibrillar collagens or enzymes that affect their intracellular or extracellular processing. The example that will be presented involves an arginine Æ cysteine substitution in type I collagen at amino acid 134 of the α 1(I) chain. The Arg residue at this position is highly conserved among vertebrates α 1(I) chains. Substituting an Arg for a Cys residue at this position has the potential to introduce disulfide bonds between α -chains leading to type I aggregates in the ER, which are usually retained in the cells. Those cross-linked molecules which are secreted lead to the assembly of type I collagen fibrils of variable diameter (some larger and some smaller fibrils) with decrease tensile strength. Below are excerpts from the scientific article. Nuytinck et al (2002) Classical Ehlers-Danlos Syndrome caused by a mutation in type I
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This note was uploaded on 09/29/2009 for the course CSB csb327 taught by Professor Ringuitte during the Fall '08 term at University of Toronto.

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5 nots - 1 Ehlers-Danlos Syndrome(EDS and Basal...

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