GRC meaning in Medical ?

The Genome Reference Consortium (GRC) is an international collective of academic and research institutes with expertise in genome mapping, sequencing, and informatics, formed to improve the representation of reference genomes. At the time the human reference was initially described, it was clear that some regions were recalcitrant to analysis with existing technology, leaving "gaps" in the known sequence. The main reason for improving the reference assemblies are that they are the cornerstones upon which all whole genome studies are based (e.g. the 1000 Genomes Project).

The GRC is a collaborative effort which interacts with various groups in the scientific community, however the primary member institutes are:

Initially the focus lies with the Human and the Mouse reference genomes, but in mid-late 2010 full maintenance and improvement of the Zebrafish genome sequence was also added to the GRC. The goal of the Consortium is to correct the small number of regions in the reference that are currently misrepresented, to close as many remaining gaps as possible and to produce alternative assemblies of structurally variant loci when necessary.

As of September 2019, the major assembly releases for human, mouse, zebrafish, and chicken are GRCh38, GRCm38, GRCz11, and GRCg6a respectively. Major assembly releases do not follow a fixed cycle, however there are "minor" assembly updates in the form of genome patches which either correct errors in the assembly or add additional alternate loci. These assemblies are represented in various genome browsers and databases including Ensembl, those in NCBI and UCSC Genome Browser.