Import.chain(hg19tohg38.over.chain) # file downloaded from ucsc

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Download ZIP. If a good case is made, I could add an option for the smoothing to rtracklayer. It would have to be a pretty good case though. Now, you might want to do a consistency check of these CNV calls with an alternative tool such as PureCN bioconductor.

Consistency with the UCSC liftOver is going to be tough, since the algorithm is not well described and the code has a restricted license. It looks like it does some smoothing and filtering on top of the chain mappings. Exactly how would take a lot of reverse engineering. Login before adding your answer. Use of this site constitutes acceptance of our User Agreement and Privacy Policy.

Try and compare the old and new coordinates in the UCSC genome browser for their respective assemblies, do they match the same gene? Yes, both coordinates match the coding sequence for the w gene from transcript CGRA. In another situation you may have coordinates of a gene and wish to determine the corresponding coordinates in another species. This is a common situation in evolutionary biology where you will need to find coordinates for a conserved gene across species to perform a phylogenetic analysis.

To start install the rtracklayer package from bioconductor, as mentioned this is an R implementation of the UCSC liftover.

The function we will be using from this package is liftover and takes two arguments as input. The first of these is a GRanges object specifying coordinates to perform the query on. This class is from the GenomicRanges package maintained by bioconductor and was loaded automatically when we loaded the rtracklayer library.

The second item we need is a chain file , which is a format which describes pairwise alignments between sequences allowing for gaps. Next all we need to do is to create our GRanges object to contain the coordinates chr and import our chain file with the function [import. We can then supply these two parameters to liftover. Try to perform the same task we just complete with the web version of liftOver , how are the results different? Both methods provide the same overall range, however using rtracklayer is not simplified and contains multiple ranges corresponding to the chain file.

Answer , these return the ranges mapped for the corresponding input element. Answer Both methods provide the same overall range, however using rtracklayer is not simplified and contains multiple ranges corresponding to the chain file.