Schema for RepeatMasker - Repeating Elements by RepeatMasker
  Database: hg38    Primary Table: rmsk    Row Count: 5,520,017
Format description: RepeatMasker .out record
fieldexampleSQL type description
bin 585smallint(5) unsigned Indexing field to speed chromosome range queries.
swScore 463int(10) unsigned Smith Waterman alignment score
milliDiv 13int(10) unsigned Base mismatches in parts per thousand
milliDel 6int(10) unsigned Bases deleted in parts per thousand
milliIns 17int(10) unsigned Bases inserted in parts per thousand
genoName chr1varchar(255) Genomic sequence name
genoStart 10000int(10) unsigned Start in genomic sequence
genoEnd 10468int(10) unsigned End in genomic sequence
genoLeft -248945954int(11) -#bases after match in genomic sequence
strand +char(1) Relative orientation + or -
repName (TAACCC)nvarchar(255) Name of repeat
repClass Simple_repeatvarchar(255) Class of repeat
repFamily Simple_repeatvarchar(255) Family of repeat
repStart 1int(11) Start (if strand is +) or -#bases after match (if strand is -) in repeat sequence
repEnd 471int(11) End in repeat sequence
repLeft 0int(11) -#bases after match (if strand is +) or start (if strand is -) in repeat sequence
id 1char(1) First digit of id field in RepeatMasker .out file. Best ignored.

Sample Rows

Note: all start coordinates in our database are 0-based, not 1-based. See explanation here.

RepeatMasker (rmsk) Track Description


This track was created by using Arian Smit's RepeatMasker program, which screens DNA sequences for interspersed repeats and low complexity DNA sequences. The program outputs a detailed annotation of the repeats that are present in the query sequence (represented by this track), as well as a modified version of the query sequence in which all the annotated repeats have been masked (generally available on the Downloads page). RepeatMasker uses the Repbase Update library of repeats from the Genetic Information Research Institute (GIRI). Repbase Update is described in Jurka (2000) in the References section below.

Display Conventions and Configuration

In full display mode, this track displays up to ten different classes of repeats:

  • Short interspersed nuclear elements (SINE), which include ALUs
  • Long interspersed nuclear elements (LINE)
  • Long terminal repeat elements (LTR), which include retroposons
  • DNA repeat elements (DNA)
  • Simple repeats (micro-satellites)
  • Low complexity repeats
  • Satellite repeats
  • RNA repeats (including RNA, tRNA, rRNA, snRNA, scRNA, srpRNA)
  • Other repeats, which includes class RC (Rolling Circle)
  • Unknown

The level of color shading in the graphical display reflects the amount of base mismatch, base deletion, and base insertion associated with a repeat element. The higher the combined number of these, the lighter the shading.

A "?" at the end of the "Family" or "Class" (for example, DNA?) signifies that the curator was unsure of the classification. At some point in the future, either the "?" will be removed or the classification will be changed.


UCSC has used the most current versions of the RepeatMasker software and repeat libraries available to generate these data. Note that these versions may be newer than those that are publicly available on the Internet.

Data are generated using the RepeatMasker -s flag. Additional flags may be used for certain organisms. Repeats are soft-masked. Alignments may extend through repeats, but are not permitted to initiate in them. See the FAQ for more information.


Thanks to Arian Smit, Robert Hubley and GIRI for providing the tools and repeat libraries used to generate this track.


Smit AFA, Hubley R, Green P. RepeatMasker Open-3.0. 1996-2010.

Repbase Update is described in:

Jurka J. Repbase Update: a database and an electronic journal of repetitive elements. Trends Genet. 2000 Sep;16(9):418-420. PMID: 10973072

For a discussion of repeats in mammalian genomes, see:

Smit AF. Interspersed repeats and other mementos of transposable elements in mammalian genomes. Curr Opin Genet Dev. 1999 Dec;9(6):657-63. PMID: 10607616

Smit AF. The origin of interspersed repeats in the human genome. Curr Opin Genet Dev. 1996 Dec;6(6):743-8. PMID: 8994846