Analysis of the distribution of CpG dinucleotides at the 5′ end of the EphA3 gene. The ratio observed/expected by chance (obs/exp) 5′-cytosine/guanine (CpG) was calculated as described by Gardiner-Garden and Frommer.25 A moving average value for percent G + C and for obs/exp CpG was calculated for each sequence using a 79-bp window moving across the sequence at 1-bp intervals. The CpG-rich regions were defined as stretches of DNA in which both the moving average of percent G + C was greater than 50 and the moving average of obs/exp CpG was greater than 0.47. Shown beneath the graph is the relative position of the EphA3 gene 5′ upstream region, first exon and part of the first intron. The positions of the enzyme restriction sites, SacII, AvaI, andPvuII, within the 1.4-kb genomic fragment are shown. These sites were used for Southern analysis of the DNA methylation state.