Genetics of the corneal dystrophies - What we have learned in the past twenty-five years

To indicate important changes in our understanding of the corneal dystrophi es. Methods. A review of the literature of the last quarter of a century. R esults. The earliest clinical classifications of the corneal dystrophies we re based on the application of clinical, biological, histochemical, and ult rastructural methods. Since then, the first great impetus to our understand ing has come from the application of techniques to map disorders to specifi c chromosome loci, using polymorphic markers. More recently, using candidat e gene and related approaches, it has been possible to identify genes causi ng several of the corneal dystrophies and the mutations responsible for the ir phenotypic variation. A notable success has been to show that several im portant "stromal" dystrophies result from mutations in the gene beta ig-h3, which encodes for the protein keratoepithelin (beta ig-h3). Conclusions. F or the corneal dystrophies, as with other inherited disorders, there is roo m for two sorts of classification system, one based mainly on clinical pres entation and the other Un an up-to-date understanding of the genetic mechan isms. They are nor mutually exclusive. Some developmental corneal disorders : are also discussed.