Genetic linkage analysis of epidermolysis bullosa simplex, Köbner type

Genetic linkage relationships between a range of marker loci and the locus for epidermolysis bullosa simplex (EBS), Köbner type, were examined in a single kindred. A positive lod score of 1.2 at theta = 0.2 was found for Fy. To test the clinical observation that Köbner and Weber-Cockayne types may be the same disease determined by different alleles, published lod scores from definite Weber-Cockayne families were added to those from this study. A lod score of 1.8 was found at theta = 0.2. This value falls to 1.5 at theta = 0.2 when all families other than Ogna type are included. The Köbner variant studied is not closely linked to GPT and is therefore distinct from EBS1 (Ogna type). Linkage analysis is consistent with an hypothesis that Köbner and Weber-Cockayne types are determined by a single locus; however, further evidence is needed before this locus can be designated EBS2 and assigned to chromosome 1.