Copyright © 1999 The American Society of Human Genetics. All rights reserved.
The American Journal of Human Genetics, Volume 65, Issue 1, 111-124, 1 July 1999
doi:10.1086/302455
Campomelic Dysplasia Translocation Breakpoints Are Scattered over 1 Mb Proximal to SOX9: Evidence for an Extended Control Region
Dietmar Pfeifer1, Ralf Kist1, 2, Ken Dewar3, Keri Devon3, Eric S. Lander3, Bruce Birren3, Lech Korniszewski4, Elke Back1 and Gerd Scherer1, 
, 
1 Institute of Human Genetics and Anthropology, Freiburg, Germany
2 Faculty for Biology, University of Freiburg, Freiburg, Germany
3 Whitehead Institute/MIT Center for Genome Research, Cambridge, MA
4 Clinic of Infants and Metabolic Diseases, Medical Academy of Warsaw, Warsaw
Address for correspondence and reprints: Dr. Gerd Scherer, Institute of Human Genetics and Anthropology, Breisacherstrasse 33, D-79106 Freiburg, GermanyAbstract
Campomelic dysplasia (CD), a skeletal malformation syndrome with or without XY sex reversal, is usually caused by mutations within the SOX9 gene on distal 17q. Several CD translocation and inversion cases have been described with breakpoints outside the coding region, mapping to locations >130 kb proximal to SOX9. Such cases are generally less severely affected than cases with SOX9 coding-region mutations, as is borne out by three new translocation cases that we present. We have cloned the region extending 1.2 Mb upstream of the SOX9 gene in overlapping bacterial-artificial-chromosome and P1-artificial-chromosome clones and have established a restriction map with rare-cutter enzymes. With sequence-tagged-site–content mapping in somatic-cell hybrids, as well as with FISH, we have precisely mapped the breakpoints of the three new and of three previously described CD cases. The six CD breakpoints map to an interval that is 140–950 kb proximal to the SOX9 gene. With exon trapping, we could isolate five potential exons from the YAC 946E12 that spans the region, four of which could be placed in the contig in the vicinity of the breakpoints. They show the same transcriptional orientation, but only two have an open reading frame (ORF). We failed to detect expression of these fragments in several human and mouse cDNA libraries, as well as on northern blots. Genomic sequence totaling 1,063 kb from the SOX9 5′-flanking region was determined and was analyzed by the gene-prediction program GENSCAN and by a search of dbEST and other databases. No genes or transcripts could be identified. Together, these data suggest that the chromosomal rearrangements most likely remove one or more cis-regulatory elements from an extended SOX9 control region.
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