AUTOSOMAL RECESSIVE CORNEA PLANA - A CLINICAL AND GENETIC-STUDY OF 78CASES IN FINLAND

Purpose: To review the literature of autosomal recessive cornea plana (RCP) and to perform a clinical and genetic study on this disorder in Finland, The 78 Finnish RCP patients represent the majority of RCP cas es worldwide; outside Finland only 35 cases have been reported. Method s: Families with RCP, particularly in northern Finland, have been foll owed up by the senior author since the 1950s and extensive genealogica l studies have been made. Results: The most typical symptoms are great ly reduced corneal refraction, 25-35 dioptres, causing strong hyperopi a, slight microcornea, an extended Limbos zone, a central, deep cornea l opacity and a marked arcus senilis, seen even before the age of 20, We present a pedigree comprising 33 affected persons with cornea plana , We have mapped the two genes for the dominantly and the recessively inherited type of cornea plana to the same region on the long arm of c hromosome 12, (12q21), Conclusions: In northern Finland RCP has a high er frequency than elsewhere, probably as a result of a strong founder effect in the population that arrived in these regions approx. 400 yea rs ago. The strong accumulation of this rare disease in these isolated areas and the strong genealogical connections between different famil ies with RCP, suggest that probably all the Finnish RCP cases are caus ed by the same mutation.