Genlocus

In genetics, the physical position of a gene in the genome, i.e. the actual gene locus, is referred to as the gene locus.

To name the gene locus, first the number of the chromosome is designated (e.g. chromosome 20). Furthermore, the chromosomal arm is designated either by the letter p for the shorter (for "petite branche") or q for the longer arm e.g. "20q".

The chromosomal region on the shorter or longer arm is identified more precisely by numbers for band and sub-band. These are separated by a dot. As an example, a "risk locus" for atopic eczema is designated "20q13.33".

This purely descriptive nomenclature gives no indication of the function of the gene.

In contrast, the designation "risk locus", e.g. for atopic eczema, is to be interpreted differently. This designates a gene locus that is associated with a disease risk.

A disease caused by a partial deletion at a gene locus can also be called a deletion syndrome.

1. Bouabe H et al,(2013) Gene targeting in mice: a review. Methods Mol Biol 1064:315-336.