Contents

1 AnVILVRS

2 Introduction

The AnVILVRS package provides an R interface to the AnVIL VRS Toolkit, a Python library for working with the Global Alliance for Genomics and Health (GA4GH) Variation Representation Specification (VRS) standard. The package allows users to translate variant identifiers from various formats (e.g., gnomAD, SPDI, HGVS, Beacon) into GA4GH VRS Allele IDs and vice versa. Additionally, it provides functionality to retrieve allele frequency data from the 1000 Genomes Project based on VRS Allele IDs.

3 Installation

To use the AnVILVRS package, you need to have Python installed on your system. The package requires Python 3.11, so ensure that you have this version installed.

Install the AnVILVRS package from Bioconductor with:

if (!requireNamespace("BiocManager", quietly = TRUE))
    install.packages("BiocManager")

BiocManager::install("AnVILVRS")

4 Loading and Setup

Load the AnVILVRS package and the reticulate package for Python integration:

library(AnVILVRS)
library(reticulate)

After installing the package, you need to set up a Python virtual environment with the required dependencies. You can do this by running the following command in R:

install_AnVILVRS(envname = "vrs_env")

5 Usage

Once the virtual environment is set up, you can use the AnVILVRS package to translate variant identifiers and retrieve allele frequency data. First, load the package and activate the virtual environment:

use_virtualenv("vrs_env", required = TRUE)

5.1 Translating Variant Identifiers

You can translate variant identifiers from various formats into GA4GH VRS Allele IDs using the get_vrs_id function. Supported formats include “gnomad”, “spdi”, “hgvs”, and “beacon”.

get_vrs_id("chr7-87509329-A-G", "gnomad")
get_vrs_id("NC_000005.10:80656509:C:TT", "spdi")
get_vrs_id("NC_000005.10:g.80656510delinsTT", "hgvs")
get_vrs_id("5 : 80656489 C > T", "beacon")

5.2 Allele Object Retrieval

You can also retrieve the VRS Allele object using the get_vrs_allele function:

allele <- get_vrs_allele("5 : 80656489 C > T", "beacon")
allele

5.3 Variant Retrieval from Allele Object

You can convert a VRS Allele object back to a variant identifier in a specified format using the get_variant_from_allele function:

get_variant_from_allele(allele, "hgvs")

5.4 Calculating Cohort Allele Frequency

5.4.1 Population Descriptor table download

The get_pop_descriptor function downloads the population descriptor file from a known Google Storage URI to the BiocFileCache. This file is used in the calculation of the Cohort Allele Frequency (CAF). The get_caf function makes use of the population descriptor .tsv file to dynamically provide a Cohort Allele Frequency based on the sub-population of interest. In our example, we will use the “USA” population code.

library(readr)
pop_desc <- get_pop_descriptor()
read_tsv(
    file = pop_desc,
    col_types = cols(
        population_descriptor_id = col_character(),
        population_descriptor = col_character(),
        subject_id = col_character(),
        country_of_recruitment = col_character(),
        population_label = col_character()
    )
)

5.4.2 SeqRepo reference data

The get_seqrepo function downloads a SeqRepo archive from a specified URI to a local directory. This is useful for setting up the SeqRepo database required by the AnVIL VRS Toolkit.

get_seqrepo(destdir = tempdir())

5.4.3 Cohort Allele Frequency (CAF) calculation

Finally, to calculate the Cohort Allele Frequency (CAF) using the 1000 Genomes Project based on a VRS Allele ID, use the get_caf function. A .gz zipped VCF file and its corresponding index file obtained from the 1000 Genomes Project is needed. It should include variants with allele frequency annotations.

use_virtualenv("vrs_env", required = TRUE)
toolkit_dir <- setup_vrs_toolkit()
vcf <- AnVILVRS:::.get_fixture_vcf()
vcf_index <- build_vrs_index()
variant_id <- "chr1-20094-TAA-T"
vrs_id <- get_vrs_id(variant_id, "gnomad")
pop_desc <- get_pop_descriptor()
get_caf(
    vrs_id = vrs_id,
    vcf = vcf,
    vcf_index = vcf_index,
    phenotype = "USA",
    pop_desc_file = pop_desc,
    toolkit_dir = toolkit_dir
)

Session Info

Click to expand session info

sessionInfo()
#> R version 4.6.0 RC (2026-04-17 r89917)
#> Platform: x86_64-pc-linux-gnu
#> Running under: Ubuntu 24.04.4 LTS
#> 
#> Matrix products: default
#> BLAS:   /home/biocbuild/bbs-3.24-bioc/R/lib/libRblas.so 
#> LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.12.0  LAPACK version 3.12.0
#> 
#> locale:
#>  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
#>  [3] LC_TIME=en_GB              LC_COLLATE=C              
#>  [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
#>  [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                 
#>  [9] LC_ADDRESS=C               LC_TELEPHONE=C            
#> [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       
#> 
#> time zone: America/New_York
#> tzcode source: system (glibc)
#> 
#> attached base packages:
#> [1] stats     graphics  grDevices utils     datasets  methods   base     
#> 
#> other attached packages:
#> [1] reticulate_1.46.0 AnVILVRS_0.99.19  BiocStyle_2.41.0 
#> 
#> loaded via a namespace (and not attached):
#>  [1] rappdirs_0.3.4       sass_0.4.10          generics_0.1.4      
#>  [4] tidyr_1.3.2          RSQLite_2.4.6        lattice_0.22-9      
#>  [7] digest_0.6.39        magrittr_2.0.5       evaluate_1.0.5      
#> [10] grid_4.6.0           bookdown_0.46        fastmap_1.2.0       
#> [13] blob_1.3.0           jsonlite_2.0.0       Matrix_1.7-5        
#> [16] AnVILGCP_1.7.0       DBI_1.3.0            BiocManager_1.30.27 
#> [19] httr_1.4.8           purrr_1.2.2          codetools_0.2-20    
#> [22] httr2_1.2.2          jquerylib_0.1.4      cli_3.6.6           
#> [25] rlang_1.2.0          dbplyr_2.5.2         bit64_4.8.0         
#> [28] cachem_1.1.0         yaml_2.3.12          otel_0.2.0          
#> [31] BiocBaseUtils_1.15.0 tools_4.6.0          memoise_2.0.1       
#> [34] dplyr_1.2.1          filelock_1.0.3       GCPtools_1.3.0      
#> [37] curl_7.1.0           vctrs_0.7.3          R6_2.6.1            
#> [40] png_0.1-9            lifecycle_1.0.5      BiocFileCache_3.3.0 
#> [43] bit_4.6.0            pkgconfig_2.0.3      pillar_1.11.1       
#> [46] bslib_0.10.0         glue_1.8.1           Rcpp_1.1.1-1.1      
#> [49] xfun_0.57            tibble_3.3.1         tidyselect_1.2.1    
#> [52] knitr_1.51           AnVILBase_1.7.0      htmltools_0.5.9     
#> [55] rmarkdown_2.31       compiler_4.6.0