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351 bytes added, 18:33, 15 July 2015
LiftOver can have three use cases:
(1) [[#Lift genome positions | convert Convert genome position from one genome assembly to another genome assembly]] 
In most scenarios, we have known genome positions in NCBI build 36 (UCSC hg 18) and hope to lift them over to NCBI build 37 (UCSC hg19).
(2) [[#Lift dbSNP rs numbers | convert Convert dbSNP rs number from one build to another]] (3) [[#Lift Merlin/PLINK format | Convert both genome position and dbSNP rs number over different versions]]
(3) [[#Lift Merlin/PLINK format |convert both genome position and dbSNP rs number over different versions]]
It is likely to see such type of data in Merlin/PLINK format.
With the above in mind, we are able to combine these two tables to obtain the relationship between older rs number and new rs number.
We have developed a script (for internal use), named [] AAAA for lift rs numbers between builds.
This scripts require RsMergeArch.bcp.gz and SNPHistory.bcp.gz, those can be found in [[#Resources | Resources]].
Example input:
Example otuputoutput:
unchanged 3115860unchanged 12124819 3000lifted 2229002 2032lifted 1130683unchanged 3002
Similar to the human reference build, dbSNP also have different versions. You may consider change rs number from the old dbSNP version to new dbSNP version
depending on your needs. Such steps are described in [[#Lift dbSNP rs numbers | Lift dbSNP rs numbers]]. AAAA
==== Method 2 ====
(2) Lookup SNP positions from rs number
dbSNP provides a file [[#Resources | joinb132_SNPChrPosOnRef_37_1b132_SNPChrPosOnRef_37_1.bcp.gz]] which contains rsNumber, chromosome and its position.
Use this file along with the new rsNumber obtained in the first step.
In practice, some rs numbers do not exist in build 132, or not suitable to be considered ( e.g. they do not reside on human reference, or they are mapped to multiple locations, these scenarios are noted by the chromosome column with values like "AltOnly", "Multi", "NotOn", "PAR", "Un"), we can drop them in the liftover procedure.
==== Method 3 ====
NCBI dbSNP team has provided a [[ #Resources | provisional map ]] AAAA for converting the genome position of a larget set dbSNP from NCBI build 36 to NCBI build 37.
In the second step, we have obtained unlifted genome positions, so we can try to use the table to convert those unlfted dbSNPs.
After this step, there are still some SNPs that cannot be lifted, as they are mostly located on non-reference chromosome.
== Resources ==
* [[]] and its interal location: /net/dumbo/net/dumbofantasia/home/zhanxw/amd/analyze/verifyBamID/
* [[]]
* NCBI provisional map [ file] and [ info]
* NCBI RgMergeArch [ file] and [ schema]
* NCBI SNPHistory [ file] and [ schema]
* NCBI SNPChrPosOnRef build 132 [ftp file] and [ schema]. If this link becomes unavailable, please consider using this updated file ([ link]). 
* How UCSC dbSNP differs from NCBI dbSNP [ UCSC dbSNP track note]
* The dbSNP mapping process [ link]
* NCBI dbSNP release 132 [ 00-All.vcf.gz]
* UCSC dbSNP release 132 [ snp132.txt.gz]
== Third party contribution ==
* liftOver for BEDPE format by [mailto:// Doug] - [].
== Acknowledge ==
Please contact [ Xiaowei Zhan].

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