pydbsnp

Interface with dbSNP VCF data

Installation

Step 0 (optional): If you don't want to bother with environment variables and don't care about how pydbsnp works under the hood, skip this step.

If you wish, you can determine the location where pydbsnp looks for relevant data using four environment variables: PYDBSNP_VCF_GRCH37, PYDBSNP_RSID_GRCH37, PYDBSNP_VCF_GRCH38, PYDBSNP_RSID_GRCH38. The VCF variables determine the location of the VCF data, the RSID variables determine the location of the rsid indices. For example, you could add this to your .bash_profile:

export PYDBSNP_VCF_GRCH37=<path of your choice>
export PYDBSNP_RSID_GRCH37=<path of your choice>
export PYDBSNP_VCF_GRCH38=<path of your choice>
export PYDBSNP_RSID_GRCH38=<path of your choice>

If you set these variables before continuing to the next step, pydbsnp will use them to determine where it places downloaded VCF files and RSID indices.

Step 1: install the python package via pip3

pip install pydbsnp

or

pip install --user pydbsnp

Step 2: Once the python package is installed, download and index the dbSBP VCF data:

pydbsnp-download
pydbsnp-index

For hg19/GRCh37 coordinates:

pydbsnp-download --reference-build GRCh37
pydbsnp-index

Command line usage

pydbsnp-query -h

pydbsnp-query rs231361
pydbsnp-query chr8:118184783
pydbsnp-query --reference-build GRCh37 rs231361
pydbsnp-query rs231361 chr8:118184783 rs7903146

API

Two classes are provided: Variant and GeneralizedVariant.

An object of the Variant class has an attribute for each relevant field of the VCF.

from pydbsnp import Variant
v = Variant(id='rs8056814')
print(v.chrom, v.pos, v.id, v.ref, v.alt)
print(v.info)
w = Variant(id='rs8056814', reference_build='GRCh37')
print(w.chrom, w.pos)
x = Variant('chr16', 75218429)
print(x)
help(Variant)

An object of the GeneralizedVariant class is similar, but each attribute is a tuple which may have multiple items. For example, one RSID may map to two sets of coordinates.

gv = GeneralizedVariant(id='rs8056814')
print(gv.chrom, gv.pos, gv.id, gv.ref, gv.alt)