VariantClassifier: A hierarchical variant classifier for annotated genomes

BACKGROUND: High-throughput DNA sequencing has produced a large number of closed and well annotated genomes. As the focus from whole genome sequencing and assembly moves towards resequencing, variant data is becoming more accessible and large quantities of polymorphisms are being detected. An easy-to-use tool for quickly assessing the potential importance of these discovered variants becomes ever important. FINDINGS: Written in Perl, the VariantClassifier receives a list of polymorphisms and genome annotation, and generates a hierarchically-structured classification for each variant. Depending on the available annotation, the VariantClassifier may assign each polymorphism to a large variety of feature types, such as intergenic or genic; upstream promoter region, intronic region, exonic region or downstream transcript region; 5' splice site or 3' splice site; 5' untranslated region (UTR), 3' UTR or coding sequence (CDS); impacted protein domain; substitution, insertion or deletion; synonymous or non-synonymous; conserved or unconserved; and frameshift or amino acid insertion or deletion (indel). If applicable, the truncated or altered protein sequence is also predicted. For organisms with annotation maintained at Ensembl, a software application for downloading the necessary annotation is also provided, although the classifier will function with properly formatted annotation provided through alternative means. CONCLUSIONS: We have utilized the VariantClassifier for several projects since its implementation to quickly assess hundreds of thousands of variations on several genomes and have received requests to make the tool publically available. The project website can be found at: http://www.jcvi.org/cms/research/projects/variantclassifier.