LOCALIZATION OF A GENE FOR AUTOSOMAL-DOMINANT LARSEN SYNDROME TO CHROMOSOME REGION 3P21.1-14.1 IN THE PROXIMITY OF, BUT DISTINCT FROM, THE COL7A1 LOCUS

Larsen syndrome (LS) is a skeletal dysplasia (osteochondrodysplasia) i n which multiple dislocations of the large joints are the major featur e. Nosology in this group of diseases, which constitutes 8% of Mendeli an disorders in man, is primarily based on clinical and radiographic f eatures, Hopes for more accurate classification grounds are currently being met by progress in elucidation of underlying genetic defects. We have performed linkage analysis in a large Swedish kindred with autos omal dominant LS and found the gene (LAR1) to be strongly linked to ch romosome 3p markers (Z(max) = 13.4 at (theta = .00). Recombination ana lysis indicates that the LAR1 locus is located in a region defined dis tally by D3S1581. and proximally by D3S1600, which cytogenetically map s to chromosome region 3p21.1-14.1. Linkage and recombination analysis of a COL7A1 PruII intragenic polymorphism versus LS and chromosome 3 markers indicate that COL7A1 is located close to, but distinct from, t he LAR1 locus.