GRCm37

GRCm37, also known as NCBIm37 or mm9, is a reference genome assembly for Mus musculus produced by the Genome Reference Consortium. It represents the 37th release in the series of publicly available mouse reference genomes and served as the standard coordinate framework for genetic and genomic analyses for several years.

GRCm37 was generated from multiple laboratory mouse strains and reflects a consensus assembly intended for broad use in research, rather than a single individual’s genome. The assembly improved contiguity and accuracy relative to earlier builds and included corrections to misassembled regions and improved chromosomal assignments. The total length is around 2.7 gigabases, with sequence assigned to autosomes 1–19, the X and Y chromosomes, and additional unplaced scaffolds.

GRCm37 is widely used as a reference for read alignment, variant detection, gene annotation, and comparative studies. It is deployed across major genomic resources, including Ensembl, the UCSC Genome Browser, and NCBI, and is compatible with historical datasets mapped to mm9/NcbI37 coordinates. Coordinate conversion tools (liftover) facilitate translation to newer assemblies.

GRCm37 has been superseded by subsequent mouse genome assemblies, most notably GRCm38 (mm10) and later releases, which incorporate further refinements and updated annotations.

The assembly and its annotations are publicly available in FASTA and annotation formats from GRC and major genome resources, and remain cited in historical studies and legacy datasets.