The chromosomal location is the physical (cytogenetic) location of a gene or region on a chromosome. In humans, it is written as the chromosome number, the p or q arm, and the position. The ‘short arm’ is referred to as p and the ‘long arm’ as q:
12p13 [chromosome 12, position 16 on the short arm] Xq3.5 [chromosome X, position 3.5 on the long arm]
If the band position is not known precisely, a range can be indicated:
8q10–q15 [chromosome 8, between position 10 and 16 on the long arm]
Other species have different ways of mapping chromosomes; see the nomenclature websites listed under Genes and gene products for guidance.
