Within the Variation and Repeats annotation group, UCSC has added several new data sets. The simple nucleotide polymorphism (SNP) data from dbSNP (15) Build 126, already available on the human and mouse assemblies, has been added to the chimp, rat, and dog. Updates to SNP Build 128 will be incorporated pending data release from dbSNP. SNP annotations may be filtered by several attributes, including average heterozygosity and weight, location type, class, validation, function and molecule type. The alignments of the SNP's flanking sequences to the genome are displayed on the details page for each SNP; in addition, the hg18 SNP details pages include the chimp and rhesus macaque orthologous alleles. We have also added a HapMap SNPs annotation (16) to the hg17 and hg18 assemblies containing data for 4 million SNPs (dbSNP 125) from four populations, together with the display of orthologous alleles from chimp and rhesus macaque and several options for filtering the data display. The Structural Variation annotation has been expanded to include structural variation data (17), deletions detected by several techniques (18–20) and numerous copy number polymorphism
