This track shows hundreds of millions of short genetic variants (up to approximately 50 base pairs) from dbSNP build 152: single-nucleotide variants (SNVs), small insertions, deletions, and complex deletion/insertions, relative to the reference genome assembly. Most variants in dbSNP are rare, not true polymorphisms, and some variants are known to be pathogenic.
For hg38 (GRCh38), approximately 655 million distinct variants (RefSNP clusters with rs# ids) have been mapped to almost 690 million genomic locations including alternate haplotype and fix patch sequences. dbSNP remapped variants from hg38 to hg19 (GRCh37); approximately 645 million distinct variants were mapped to over 670 million genomic locations including alternate haplotype and fix patch sequences (not all of which are included in UCSC's hg19).