All SNPs(150) Track Settings
 
Simple Nucleotide Polymorphisms (dbSNP 150)   (All Variation tracks)

Display mode:   

Include Chimp state and observed human alleles in name:  
(If enabled, chimp allele is displayed first, then '>', then human alleles).
  Show alleles on strand of reference genome reported by dbSNP:  

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Data last updated at UCSC: 2020-06-15

Description

This track contains information about single nucleotide polymorphisms and small insertions and deletions (indels) — collectively Simple Nucleotide Polymorphisms — from dbSNP build 150, available from ftp.ncbi.nlm.nih.gov/snp.

Three tracks contain subsets of the items in this track:

  • Common SNPs(150): SNPs that have a minor allele frequency of at least 1% and are mapped to a single location in the reference genome assembly. Frequency data are not available for all SNPs, so this subset is incomplete.
  • Flagged SNPs(150): SNPs flagged as clinically associated by dbSNP, mapped to a single location in the reference genome assembly, and not known to have a minor allele frequency of at least 1%. Frequency data are not available for all SNPs, so this subset may include some SNPs whose true minor allele frequency is 1% or greater.
  • Mult. SNPs(150): SNPs that have been mapped to multiple locations in the reference genome assembly. There are very few SNPs in this category because dbSNP has been filtering out almost all multiple-mapping SNPs since build 149.

The default maximum weight for this track is 1, so unless the setting is changed in the track controls, SNPs that map to multiple genomic locations will be omitted from display. When a SNP's flanking sequences map to multiple locations in the reference genome, it calls into question whether there is true variation at those sites, or whether the sequences at those sites are merely highly similar but not identical.

The remainder of this page is identical on the following tracks:
  • Common SNPs(150) - SNPs with >= 1% minor allele frequency (MAF), mapping only once to reference assembly.
  • Flagged SNPs(150) - SNPs < 1% minor allele frequency (MAF) (or unknown), mapping only once to reference assembly, flagged in dbSnp as "clinically associated" -- not necessarily a risk allele!
  • Mult. SNPs(150) - SNPs mapping in more than one place on reference assembly.
  • All SNPs(150) - all SNPs from dbSNP mapping to reference assembly.

Interpreting and Configuring the Graphical Display

Variants are shown as single tick marks at most zoom levels. When viewing the track at or near base-level resolution, the displayed width of the SNP corresponds to the width of the variant in the reference sequence. Insertions are indicated by a single tick mark displayed between two