Diastrophic dysplasia gene maps to the distal long arm of chromosome 5.

We have used polymorphic DNA markers to map the gene for a clinically well-characterized form of osteochondrodysplasia, diastrophic dysplasia (DD), an autosomal recessive disorder of unknown pathogenesis. Linkage was analyzed in 13 families with two or three affected sibs comprising a total of 84 individuals. Positive two-point logarithm-of-odds (lod) scores were obtained between the DD locus and three polymorphic markers on chromosome 5. The highest pairwise lod score estimate of 7.37 with zero recombination to locus D5S72 suggests very tight linkage. There was no evidence of heterogeneity. Multipoint linkage analysis against the published order of the three loci gave the result centromere-D5S84-(DD, D5S72)-D5S61-terminus with a four-point lod score of 9.11. The present findings place the DD locus distal to the gene for adenomatous polyposis coli on the distal part of the long arm of chromosome 5. Our results provide a basis for refining the map position of the DD locus followed by physical localization, isolation, and characterization of the gene.