## Description

This track indicates differences in this human genome assembly, (GRCh37/hg19), from the previous version, NCBI Build 36 (hg18). Contigs used in the assembly of GRCh37 (hg19) that were not present in NCBI Build 36 (hg18) are shown.

The following color/score key is used:

color | score | change from hg18 to hg19
--- | --- | ---
| 0 | New contigs added to hg19 to update sequence or fill in gaps from hg18
| 500 | Different portion of the same contig used in hg19 compared to hg18
| 1000 | Updated version of the same contig used in hg19 to correct errors in the hg18 sequence

You can use the score filter to eliminate or include the different categories in the display.

## Methods

The contig coordinates were extracted from the AGP files for the assemblies. Contigs that match the same name, same version, and the same specific portion of sequence are noted as identical in the two assemblies. Contigs not satisifying those identical characteristics are included in this track.

## Credits

The data and presentation of this track were prepared by Hiram Clawson, UCSC Genome browser engineering.