The mutation involved in myotonic dystrophy (DM) has been mapped to the region between the ERCC1 DNA repair gene and the anonymous D19S51 locus on 19q13.3. Starting at locus D19S112 (probe pX75b), which served as a novel entry site for this chromosome region, we have established a cosmid contig of approximately 200 kb. In the contig, a gene expressed in the brain and a highly informative, 12-allele (TG)n variable simple sequence motif (VSSM) were identified. With this marker, designated X75b-VSSM, a highly characteristic size distribution of alleles linked with DM, which differed significantly from that on normal chromosomes, was observed. Combining our physical mapping and genetic data, we show that the X75b-VSSM marker is the closest distal to DM, thus excluding the DM mutation from the entire telomeric portion of the ERCC1-D19S51 region.
Bibliographical noteFunding Information:
Marga Coerwinkel-Driessen, Frank Oerlemans, and Jennifer Alle-man are gratefully acknowledged for technical assistance with DNA typing, tissue culture, and cosmid pool preparation. We thank R. de Graaf for conducting the statistical calculations. Work performed at the University of Nijmegen was supported by the American Muscular Dystrophy Association, the Prinses Beatrixfonds, Grant 87-2694 and by Grant Ro 389/l&3 from the Deutsche Forschungsgemeinschaft. Work performed at the Lawrence Livermore National Laboratory was performed under the auspices of the U.S. Department of Energy under Contract W-7405-ENG-48.