If the genome consists of several chromosomes , the gene locus is the location on the chromosome where the gene is located. Different expressions or variants of this gene are also referred to as alleles that are assigned to the same gene location. The term originated when the first gene maps were created and is linked to the knowledge that genes have specific positions in the arrangement on the chromosomes.
To name such a gene location, first name the number of the chromosome, then mark the chromosome arm in relation to the centromere - either with the letter p for the shorter arm ( French petite branch , small arm ) or q for the longer arm - and finally enter the chromosomal region on this arm is indicated more precisely by numbers for the bands and sub-bands, the latter separated by a point. For example, the gene locus 22q12.2 is marked in red in the adjacent drawing.
This nomenclature gives no indication of the function of the gene - unlike names such as Hox-Gen or MYH9 - and only describes the location. For example, one can say that the MYH9 gene for the protein myosin -9 (also myosin, heavy chain 9 non-muscle or MYH9) is located in humans at the gene locus 22q12.3 or 22q13.1. Or a disease that is caused by a partial deletion at the 1q21.1 gene location can be referred to as 1q21.1 deletion syndrome.
- see entry UniProtKB - P35579 (MYH9_HUMAN) in the database for proteins UniProt .
- UCSC Genome Browser on Human, Dec 2013: chr22: 36,281,281-36,388,018 .
- Location of MYH9 according to HUGO , accessed on March 1, 2016.