In humans, the chromosomes occur in pairs and a typical somatic cell would contain 23 pairs of chromosomes in the nucleus. Each of these pairs has a characteristic length and banding pattern. There are two types of chromosomes: autosomes and allosomes. There are also two sets: the first set comes from the mother and the second set, from the father. Using idiograms, each chromosome may be identified one from the other based on the relative size and the banding pattern.
Chromosome 12 is a submetacentric autosome. It spans almost 133 million base pairs (i.e. about 4 to 4.5 % of the total DNA). It is likely to have about 900 or less than 1100 genes. Some of the genes in this chromosome are CALCOCO1 (coding for calcium-binding and coiled-coil domain-containing protein 1), CKAP4 (for cytoskeleton associated protein 4), MYO1A (for myosin IA), and PAH (for phenylalanine hydroxylase).
Some of the diseases and disorders related to the genes on chromosome 12 include achondrogenesis type 2, hypochondrogenesis, Noonan syndrome, and stuttering.