LiFD

Pipeline to identify LiFDs (Likely Functional Drivers)

See corresponding papers for full details Reiter et al, An analysis of genetic heterogeneity in untreated cancers (Nature Reviews Cancer, 2019) and Reiter, Makohon-Moore, Gerold et al, Minimal functional driver gene heterogeneity among untreated metastases (Science, 2018)

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What is LiFD?

LiFD is a two-phase algorithm to predict likely functional driver (LiFD) mutations that integrates information from multiple databases and bioinformatic methods.
During the first phase of LiFD, variants that are present in OncoKB, the catalog of validated oncogenic mutations (CGI, Cancer Genome Interpreter; driver prediction “known”), known cancer hotspots, or present at least 4 times in COSMIC (Catalogue of Somatic Mutations in Cancer) are annotated as functional.
If a variant is not annotated as functional in the first phase, LiFD uses CHASMplus, FATHMM, CanDrA+, CGI, and VEP to predict the functional consequences of individual mutations in the second phase.
By default, LiFD requires a q-value of at most 0.1 for CHASMplus.
For FATHMM, LiFD uses the recommended threshold of at most -0.75.
For CanDrA, LiFD uses a significance threshold of 0.05 for driver predictions.
For CGI, LiFD requires “predicted” in its driver classification column and for VEP LiFD requires “HIGH” in its predicted impact column.
If the majority (>50%) of the methods that produce a valid result predict functionality, LiFD annotates the mutation as likely functional and otherwise as unlikely functional.
Default reference genome is hg19. Only some of the pooled tools support hg20.

Note: Setting up LiFD with all its dependencies is painful and very time consuming.
You may want to focus just on a few tools and databases that are well maintained.
In our experience, CHASMpluas was easy to install and also performed very well.

Releases

Installation and Setup

1. Install Python 3.6 (https://www.python.org/downloads). Check installation with which python3.6. Load Python 3.6 with ml python/3.6 if installing LiFD onto a remote server/cluster.
2. Install PyEnsembl (https://github.com/openvax/pyensembl) and Varcode (https://github.com/openvax/varcode), used for mutation effect annotation, with pip install pyensembl varcode. Run pyensembl install --release 75 --species human to get the latest genome database for hg19/GRCh37.
3. Open a terminal and clone the repository from GitHub with git clone https://github.com/johannesreiter/LiFD.git.
   If you want to have system-wide access, create distribution packages by going into the main folder with cd <LiFD_directory>, run python3 setup.py clean sdist bdist_wheel and
   and install LiFD to your python environment by running pip3.6 install -e <LiFD_directory>
4. Test installation by opening a python shell python3.6 and execute these commands import lifd and lifd.__version__. As output you should get your current LiFD version. You can also run the unit tests with python3 -m unittest discover <LiFD_directory>/. Exit the shell with exit().

Running LiFD when functional annotation is provided

$ lifd -i <INPUT_FILE> [--driver_genes=<driver_gene_file>] [--verbose] [--hotspots] [--oncokb] [--cosmic] [--oncogenic] [--vep] [--cravat] [--fathmm] [--candra] [--cgi] [--cgi_username=<YOUR CGI USERNAME>] [--cgi_token=<YOUR CGI TOKEN>]

$ lifd -i lifd_examples/example_variants.xlsx --hotspots --oncokb --cosmic --oncogenic --vep --cravat --cgi --fathmm --candra

Running LiFD when functional annotation is missing

LiFD takes as input either a CSV, TSV, or an Excel file with the following required columns: Chromosome, StartPosition, EndPosition, ReferenceAllele, and AlternateAllele.
See lifd_examples/example_variants.xlsx for format.
Some predictors also require a CancerType column according to the TCGA abbreviations (https://gdc.cancer.gov/resources-tcga-users/tcga-code-tables/tcga-study-abbreviations).
If boolean column MaybeFunctional (denoting whether variant is a nonsynonymous or splice-site mutation) is not provided, then VarCode will be invoked.
For an ipython notebook example see lifd_examples/lifd_examples.ipynb.
To run LiFD from the command line see above.

Download the following databases into a directory and set variable DB_DIR with path to the databases in lifd/settings.py:

• OncoKB v1.21: apply to get access to their database at (https://www.oncokb.org/); previously the data was freely available (https://github.com/oncokb/oncokb-public/tree/master/data). Set variable ONCOKB_ALLVARS_FP with path to downloaded file in lifd/settings.py accordingly.
• Cancer Hotspots V2 (https://www.cancerhotspots.org/#/download). Set variable HOTSPOTS_FP with path to downloaded file in lifd/settings.py accordingly. Note that in the original study, version 1 of the hotspots were used.
• COSMIC Mutation Data Genome Screens v89 (https://cancer.sanger.ac.uk/cosmic/download?genome=37). Set variable COSMIC_VARS_FP with path to downloaded file in lifd/settings.py accordingly. Note that in COSMIC release v90 many things were changed and the strand information is now always positive inconsistent with previous releases. Release v91 will fix this issue again.
• CGI Catalog of Validated Oncogenic Mutations (https://www.cancergenomeinterpreter.org/mutations). Set variable ONCOGENIC_VARS_FP with path to downloaded file in lifd/settings.py accordingly.

Install Pysam (https://github.com/pysam-developers/pysam), used to find reference alleles for indels, with pip3.6 install pysam. Download a fasta file for hg19 (http://hgdownload.cse.ucsc.edu/goldenPath/hg19/bigZips/hg19.fa.gz) into the database directory.

Setup the predictive tools (and their cancer-specific models) to create annotations for LiFD automatically:

• CanDrA.v+ (https://bioinformatics.mdanderson.org/main/CanDrA)

• CRAVAT and CHASMplus (https://chasmplus.readthedocs.io/en/latest/)

• CGI is a web tool and no installation is required. However, a login needs to be created at (https://www.cancergenomeinterpreter.org). A file cgi_settings.py containing the credentials is expected at lifd/cgi_settings.py in the following format:

  CGI_USER_ID = '<YOUR USERNAME>'
  CGI_TOKEN = '<YOUR CGI TOKEN>'
  

• FATHMM (http://fathmm.biocompute.org.uk/downloads.html)

  • The files for FATHMM (fathmm.py and config.ini) should be located under DB_DIR in the folder fathmm/cgi-bin. The following edits should be made to fathmm.py to make the file compatible with Python 3, if desired:
    • Change all lines “except Exception, e:” to “except Exception as e:”
    • Change line “import ConfigParser” to “import configparser as ConfigParser”
  • FATHMM requires MySQL (https://www.mysql.com/downloads/) or MariaDB. If using MariaDB, which is common for remote servers/clusters, make the additional change below to replace the line that initializes dbCursor:

    mariadb_connection = mariadb.connect(
      host = str(Config.get("DATABASE", "HOST")), 
      port = int(Config.get("DATABASE", "PORT")), 
      unix_socket = int(Config.get("DATABASE", "UNIX_SOCKET")), 
      user = str(Config.get("DATABASE", "USER")), 
      password = str(Config.get("DATABASE", "PASSWD")), 
      database = str(Config.get("DATABASE", "DB")))
    dbCursor = mariadb_connection.cursor(dictionary = True)
    

    Load MariaDB with ml system mariadb.
    If using MySQL, start server with mysql.server start
  • Check the line COMMAND = 'python3 fathmm.py -w Cancer {} {}' in lifd/predictors/fathmm.py and correct the line to reflect the version of Python. Note that a separate installation of Python 2 will be necessary to run fathmm.py if the above corrections are not made.
  • As written on the FATHMM installation page, place information about the user, database, etc. in config.ini file as follows:

  [DATABASE]
  HOST   = <MySQL Host>
  PORT   = <MySQL Port>
  USER   = <MySQL Username>
  PASSWD = <MySQL Password>
  DB     = fathmm
  

  It may be necessary to add UNIX_SOCKET = <MySQL/MariaDB Socket> to the FATHMM config file, especially for a remote server implementation. On a remote server, run mysqld_safe on the command line to start a mysqld server, which blocks for MySQL commands. Terminal multiplexers such as tmux are espsecially useful for this task.

  • Download MySQLdb with pip install MySQL-python for Python 2 and pip install mysqlclient for Python 3 if using MySQL. For MariaDB, download mysql.connector with pip install mysql-connector-python. Delete all import MySQLdb statements and insert import mysql.connector as mariadb in the downloaded fathmm.py file.

• VEP (https://uswest.ensembl.org/info/docs/tools/vep/script/vep_download.html)

  • VEP requires Perl (https://www.perl.org/get.html) and MySQL (https://www.mysql.com/downloads/). In a remote server, load Perl and MariaDB with ml perl and ml system mariadb, respectively. Install the required Perl packages (Archive::Zip, DBD::mysql, DBI) with cpanm [package] before running the VEP setup file with perl INSTALL.pl. The directory of the cache can be assigned with an optional argument (--CACHEDIR [dir]) during setup. Set variable VEP_CACHE with path to VEP cache (initially set to the default location of the cache).
  • Note that some dependencies of various Perl packages may fail during either installation of the requirements or the setup, such as Test::Pod::Coverage or XML::DOM::XPath; keep track of these packages and install them separately, possibly using --force argument to circumnavigate outdated tests. Dependencies of dependencies may also fail, in which case this process should be repeated.
  • Note that many packages may already exist on a remote server. Load some of the packages with ml libgd and ml biology htslib.

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Problems?

If you have any questions, you can contact us (https://github.com/johannesreiter) and we will try to help.

License

Copyright © 2019 Johannes Reiter

LiFD is licensed under the GNU General Public License, Version 3.
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation,
version 3 of the License.
There is no warranty for this free software.

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Author: Johannes G. Reiter, Stanford University, https://reiterlab.stanford.edu