PMCID: PMC3965024 Supplementary Data are available at NAR online, including [18–25]. ; Locus Reference Genomic (LRG; http://www.lrg-sequence.org/) records contain internationally recognized stable reference sequences designed specifically for reporting clinically relevant sequence variants. Each LRG is contained within a single file consisting of a stable 'fixed' section and a regularly updated 'updatable' section. The fixed section contains stable genomic DNA sequence for a genomic region, essential transcripts and proteins for variant reporting and an exon numbering system. The updatable section contains mapping information, annotation of all transcripts and overlapping genes in the region and legacy exon and amino acid numbering systems. LRGs provide a stable framework that is vital for reporting variants, according to Human Genome Variation Society (HGVS) conventions, in genomic DNA, transcript or protein coordinates. To enable translation of information between LRG and genomic coordinates, LRGs include mapping to the human genome assembly. LRGs are compiled and maintained by the National Center for Biotechnology Information (NCBI) and European Bioinformatics Institute (EBI). LRG reference sequences are selected in collaboration with the diagnostic and research communities, locus-specific database curators and mutation consortia. Currently >700 LRGs have been created, of which >400 are publicly available. The aim is to create an LRG for every locus with clinical implications. ; The Wellcome Trust [WT095908]; British Heart Foundation [SP/10/10/28431]; European Molecular Biology Laboratory. European Community’s Seventh Framework Programme [FP7/2007-2013] under grant agreement number 200754–the GEN2PHEN project. Work at NCBI is supported by the National Institutes of Health Intramural Research Program and the National Library of Medicine. Funding for open access charge: The Wellcome Trust. ; Peer-reviewed ; Publisher Version