The Ehlers-Danlos syndromes.

The Ehlers-Danlos syndromes (EDS) are a heterogeneous group of inherited connective tissue disorders characterized clinically by skin fragility, skin hyperextensibility, joint hypermobility, and excessive bruising. At least 10 different subtypes of EDS have been classified based on genetic, biochemical, and clinical characteristics. Recent advances in the molecular analysis of EDS have identified defects responsible for EDS IV (mutations in the type III collagen gene), EDS VI (homozygous and compound heterozygous mutations in the lysyl hydroxylase gene), EDS VIIA and VIIB (mutations in the type I collagen genes), EDS VIIC (deficiency of procollagen N-proteinase), and EDS IX (decreased lysyl oxidase activity). Very little is known about the genetic or biochemical defects responsible for the other EDS subtypes, but with the application of the tools of molecular biology, analysis of these defects is now within reach.