This directory contains FASTA files which contain a modified version
of the Genome Reference Consortium human genome build 37 (hg19, Feb. 2009). 
The chromosomal sequences were assembled by the International Human 
Genome Project sequencing centers.  The hg19/GRCh37 assembly was changed 
to use IUPAC ambiguous nucleotide characters at each base covered by a 
stringently filtered subset of single-base substitutions annotated by 
dbSNP build 131.  For example, if the assembly has an 'A' at a position 
where dbSNP has annotated an A/C/T substitution SNP, the 'A' is replaced 
by 'H' in the FASTA file here.  

dbSNP single-base substitutions were excluded from masking in the
following cases:
- UCSC tagged the dbSNP item with any of these exceptions (see also
  hg19.snp131Exceptions and hg19.snp131ExceptionDesc database tables):
  - MultipleAlignments: dbSNP mapped item to multiple locations
  - ObservedMismatch: the reference allele does not appear in the item's
    observed alleles.
  - ObservedWrongFormat: the observed sequence has an unexpected format
    (no instances of this exception were found in snp131)
- dbSNP item class is not "single".
- dbSNP item length is not exactly one base.
- dbSNP item weight is greater than 1.  (lower weight = higher confidence)
The remaining single-base substitutions were used to mask the genomic 
sequence.

Files included in this directory:

chr*.subst.fa.gz - FASTA files with IUPAC characters for substitution SNPs

md5sum.txt - checksums of files in this directory

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If you plan to download a large file or multiple files from this
directory, we recommend that you use ftp rather than downloading the
files via our website. To do so, ftp to hgdownload.cse.ucsc.edu
[username: anonymous, password: your email address], then cd to the
directory goldenPath/hg19/bigZips. To download multiple files, use
the "mget" command:

    mget <filename1> <filename2> ...
    - or -
    mget -a (to download all the files in the directory)

Alternate methods to ftp access.

Using an rsync command to download the entire directory:
    rsync -avzP rsync://hgdownload.cse.ucsc.edu/goldenPath/hg19/snp131Mask/ .
For a single file, e.g. chr1.subst.fa.gz
    rsync -avzP \
        rsync://hgdownload.cse.ucsc.edu/goldenPath/hg19/snp131Mask/chr1.subst.fa.gz .

Or with wget, all files:
    wget --timestamping \
        'ftp://hgdownload.cse.ucsc.edu/goldenPath/hg19/snp131Mask/*'
With wget, a single file:
    wget --timestamping \
        'ftp://hgdownload.cse.ucsc.edu/goldenPath/hg19/snp131Mask/chr1.subst.fa.gz' \
        -O chr1.subst.fa.gz

To uncompress the fa.gz files:
    gunzip <file>.fa.gz

      Name                       Last modified      Size  Description
Parent Directory - md5sum.txt 2010-05-27 16:32 3.5K chrY.subst.fa.gz 2010-05-27 14:29 8.0M chrX.subst.fa.gz 2010-05-27 14:29 48M chrUn_gl000248.subst.fa.gz 2010-05-27 14:29 13K chrUn_gl000247.subst.fa.gz 2010-05-27 14:29 12K chrUn_gl000246.subst.fa.gz 2010-05-27 14:29 13K chrUn_gl000245.subst.fa.gz 2010-05-27 14:29 12K chrUn_gl000244.subst.fa.gz 2010-05-27 14:29 13K chrUn_gl000243.subst.fa.gz 2010-05-27 14:29 14K chrUn_gl000241.subst.fa.gz 2010-05-27 14:29 14K chrUn_gl000240.subst.fa.gz 2010-05-27 14:29 14K chrUn_gl000239.subst.fa.gz 2010-05-27 14:29 10K chrUn_gl000238.subst.fa.gz 2010-05-27 14:29 13K chrUn_gl000237.subst.fa.gz 2010-05-27 14:29 14K chrUn_gl000236.subst.fa.gz 2010-05-27 14:29 14K chrUn_gl000235.subst.fa.gz 2010-05-27 14:29 12K chrUn_gl000234.subst.fa.gz 2010-05-27 14:29 14K chrUn_gl000233.subst.fa.gz 2010-05-27 14:29 14K chrUn_gl000232.subst.fa.gz 2010-05-27 14:29 14K chrUn_gl000231.subst.fa.gz 2010-05-27 14:29 9.4K chrUn_gl000230.subst.fa.gz 2010-05-27 14:29 13K chrUn_gl000229.subst.fa.gz 2010-05-27 14:29 6.7K chrUn_gl000228.subst.fa.gz 2010-05-27 14:29 33K chrUn_gl000227.subst.fa.gz 2010-05-27 14:29 41K chrUn_gl000226.subst.fa.gz 2010-05-27 14:29 3.5K chrUn_gl000225.subst.fa.gz 2010-05-27 14:29 58K chrUn_gl000224.subst.fa.gz 2010-05-27 14:29 51K chrUn_gl000223.subst.fa.gz 2010-05-27 14:29 57K chrUn_gl000222.subst.fa.gz 2010-05-27 14:29 60K chrUn_gl000221.subst.fa.gz 2010-05-27 14:29 51K chrUn_gl000220.subst.fa.gz 2010-05-27 14:29 54K chrUn_gl000219.subst.fa.gz 2010-05-27 14:29 59K chrUn_gl000218.subst.fa.gz 2010-05-27 14:29 55K chrUn_gl000217.subst.fa.gz 2010-05-27 14:29 56K chrUn_gl000216.subst.fa.gz 2010-05-27 14:29 43K chrUn_gl000215.subst.fa.gz 2010-05-27 14:29 56K chrUn_gl000214.subst.fa.gz 2010-05-27 14:29 44K chrUn_gl000213.subst.fa.gz 2010-05-27 14:29 53K chrUn_gl000212.subst.fa.gz 2010-05-27 14:29 62K chrUn_gl000211.subst.fa.gz 2010-05-27 14:29 56K chrM.subst.fa.gz 2010-05-27 14:29 6.0K chr22.subst.fa.gz 2010-05-27 14:27 11M chr21.subst.fa.gz 2010-05-27 14:27 11M chr20.subst.fa.gz 2010-05-27 14:27 19M chr19.subst.fa.gz 2010-05-27 14:27 17M chr18.subst.fa.gz 2010-05-27 14:27 24M chr17.subst.fa.gz 2010-05-27 14:26 25M chr16.subst.fa.gz 2010-05-27 14:26 25M chr15.subst.fa.gz 2010-05-27 14:26 26M chr14.subst.fa.gz 2010-05-27 14:26 28M chr13.subst.fa.gz 2010-05-27 14:26 31M chr12.subst.fa.gz 2010-05-27 14:26 42M chr11.subst.fa.gz 2010-05-27 14:25 42M chr10.subst.fa.gz 2010-05-27 14:25 42M chr9.subst.fa.gz 2010-05-27 14:29 39M chr8.subst.fa.gz 2010-05-27 14:29 46M chr7.subst.fa.gz 2010-05-27 14:29 50M chr6.subst.fa.gz 2010-05-27 14:29 54M chr5.subst.fa.gz 2010-05-27 14:28 57M chr4.subst.fa.gz 2010-05-27 14:28 61M chr3.subst.fa.gz 2010-05-27 14:28 63M chr2.subst.fa.gz 2010-05-27 14:27 77M chr1.subst.fa.gz 2010-05-27 14:25 72M