Locus
Geneticists use a standardized way of describing a gene’s cytogenetic location. In most cases, the location describes the position of a particular band on a stained chromosome:
Geneticists use a standardized way of describing a gene’s cytogenetic location. In most cases, the location describes the position of a particular band on a stained chromosome:
17q12 or it can also be written as a range of bands, if less is known about the exact location: 17q12-q21
The combination of numbers and letters provide a gene’s “address” on a chromosome. This address is made up of several parts:
17: chromosome 17
q: long arm (quaque)
p: short arm (petit)
12: region 1, band 2, which are sometimes followed by a decimal point and one or more additional digits (representing sub-bands within a light or dark area). The number indicating the gene position increases with distance from the centromere. For example: 17q21 represents position 21 on the long arm of chromosome 17 is closer to the centromere than 17q22.
19q13.3 means long arm of chromosome 19, region 1, band 3, and sub-band 3.