A chromosome 1-specific region. (A) This region was selected in the following way: 18-mers were identified whose chromosome 1 counts were ≥90% of their whole genome counts. These 18-mers were strung together to create “chromosome-specific repeats” as long as the space between them was less than 100 bp. At the top of the figure are the coordinates of this region in the June 2002 assembly. Along the x-axis is the relative position of a given 18-mer within these coordinates. Along the y-axis is the absolute word count, with whole-genome counts drawn in gray and chromosome 1 counts in blue. Word counts are truncated at 100. Underneath the terrain, repeats detected by RepeatMasker are annotated in orange. Highlighted in purple are RefSeq exons that overlap this region from RefSeq gene NM_015383. (B) The chromosome-wide distribution of this family of chromosome-specific repeats, as viewed in the UCSC Genome Browser. The entire length of chromosome 1 is shown, with the purple “family” track indicating recurrences of this repeat. Below the family track are tracks that indicate both the positions of RefSeq genes and RepeatMasker annotations along chromosome 1.