Gene Address on Chromosome

Molecule Tutorials - Herong's Tutorial Examples

∟Gene Address on Chromosome

This section provides a quick introduction of the address of a human gene to specify its location on human karyotype.

The address (or location) of a specific gene on a Chromosome is expressed as a cytogenetic location in a standard format shown below:

<chromosome><arm><region><band><sub-band>

where:
  chromosome - Is the index of the chromosome in the karyotype.
  arm - Is "p" or "q", indicating the short arm or the long arm.
  region - Is the index of the region in the arm.
  band - Is the index of the band in the region.
  sub-band - Is the index of the sub-band in the band.

Note that each chromosome is divided into two sections (arms) based on the location of a narrowing (constriction) called the centromere. By convention, the shorter arm is called "p", and the longer arm is called "q".

The indexes of region, bands, and sub-bands are all counted in the direction from the centromere to the end of the arm.

The picture (source: ghr.nlm.nih.gov) below shows an example of the address of gene CFTR (Cystic Fibrosis Transmembrane conductance Regulator): 7q31.2