GENETIC-LINKAGE OF PROGRESSIVE PSEUDORHEUMATOID DYSPLASIA TO A 3-CM INTERVAL OF CHROMOSOME 6Q22

Progressive pseudorheumatoid dysplasia (PPD), MIM 208230, is an autoso mal-recessive disorder, clinically characterized by spondyloepiphyseal dysplasia and progressive arthropathy. Linkage analysis of three fami lies of different geographic and ethnic origin, including 11 affected individuals, showed strong evidence for localization of a gene for pro gressive pseudorheumatoid dysplasia to chromosome 6q with a maximum tw o-point lod score for D6S1647 of 8.34 at theta = 0. Analysis of region s of homozygosity placed the gene in a 3-cM interval between D6S1594 a nd D6S432, No significant shared haplotype was found for markers of th e linked interval In the three families analyzed. Five genes encoding collagen and one encoding a specific procollagen-processing enzyme tha t map near this interval represent good candidates for the PPD gene.