FINE MAPPING OF THE EDA GENE - A TRANSLOCATION BREAKPOINT IS ASSOCIATED WITH A CPG ISLAND THAT IS TRANSCRIBED

In order to identify the gene for human X-linked anhidrotic ectodermal dysplasia (EDA), a translocation breakpoint in a female with t(X;1)(q 13.1;p36.3) and EDA (patient AK) was finely mapped. The EDA region con tains five groups of rare-cutter restriction sites that define CpG isl ands. The two more centromeric of these islands are associated with tr anscripts of 3.5 kb and 1.8 kb. The third CpG island maps within <1 kb of the translocation breakpoint in patient AK, as indicated by a geno mic rearrangement, and similar to 100 kb centromeric from another prev iously mapped translocation breakpoint (patient AnLy). Northern analys is with a probe from this CpG island detected an similar to G-kb mRNA in several fetal tissues tested. An extended YAC contig of 1,200 kb wi th an average of fivefold coverage was constructed. The two most telom eric CpG islands map 350 kb telomeric of the two translocations. Taken together, the results suggest that the CpG island just proximal of th e AK translocation breakpoint lies at the 5' end of a candidate gene f or EDA.