CONSTRUCTION OF THE PHYSICAL MAP AT DARIER DISEASE GENE REGION ON CHROMOSOME 12Q AND AN ATTEMPT TO DETECT THE GENOMIC DELETION IN THIS REGION ON THE DNA OF PATIENTS.

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In 1993, the gene for Darier's disease (DAR) was mapped to ch12q23-24.1 by genetic linkage analysis of the kindreds of European and Middie-eastern ancestory. Since then, tremendous effort has been made to clone the gene by several researchers. As yet, however, the gene has not been cloned.Accordingly, in 1996-7, we provided basic data thought to be essential for the cloning of DAR.The summary of our data is as follows ; (1) We have tested Japanese family with this disease, and found that locus heterogeneity might be also uncommon in Japanese kindred. (2) By testing several newly isolated polymorhic DNA markers, DAR sublocalized to two megabase interval between D12S1328 and D12S1616.(3) A genomic contig encompassing the DAR region has been established. The most centromeic and telomeric portions of the contig were mainly established by us, while the central portion was established by our collabolators (Pulst S.et al : Nature Genetics, 14 : 269,1996).(3) The exon-intron junctions of serine/threonine protein phosphatase gene, while appeared to locallze to the DAR region, were sequenced, and SSCP analysis was performed in some patients. As yet, abnormalities have not been found. We are now testing for muation detection in additional several patients. (4) In order to isolate "candidate" genes, we have performed the exon-trapping method on some genomic clones on the contig. A few expressed sequnces were detected in the preliminary procedure, and tests are now underway furthetr to delimit the range of possible 'candidates'.(5) Finally, genomic DNA samples from 26 unrelated patients have been tested to identity genomic deletion using pulse-field electrophoresis + Southern hybridization with several probes obtained from the contig. As yet, abnormalities have not been found. We are in the process of isolating additional probes, which will be used to detect genomic deletion in the DNA of some patiants.