However, in relatively small or isolated feral cat populations the mutations can also spread without human intervention, for example on islands.
To protect the animal’s welfare it is illegal in several countries or states to breed with parent cats that bear certain of these hypertype mutations.
A germ-cell mutation occurred in a male Persian cat called Treker in 1995, resulting in diminutive, but healthy and normally-proportioned, offspring.
Toy and Teacup Persians are a separate breed and not all cats advertised under those names result from Treker's dominant mutation.
Furthermore, several countries or states have prohibited breeding with certain of the genetic mutations in cats, including Scotland,[17][18] Victoria and the Australian Capital Territory (Australia),[19][20] Austria,[21][22] and Flanders (Belgium).