Breeds and Genetic Diseases

Breeders use the laws of genetics to select for specific features such as color or body type. Unfortunately, they may also unwittingly select for other hidden, dangerous genes.

This is how genetic diseases gain ground in purebred lines. To name only a few of these:several breeds are prone to the lethal disease amyloidosis; certain lines of Persians suffer from poly cystic kidney disease.

Persians have a marked incidence of cataracts; Abyssinians can develop retinal degeneration; the Devon Rex carries a spastic muscular disorder; and some Burmese suffer from flat-chested syndrome, episodic weakness syndrome, and a lethal head malformation.

In natural selection for survival of the fittest, such dangerous genes are removed from the gene pool or persist at a very low level; selective breeding has allowed them to survive and be passed on.

This is the greatest genetic problem facing cats; responsible breeders now investigate genetics as part of their breeding programs. Scientists are learning more about cats' genetics.

The National Cancer Institute in the United States has a gene-mapping project investigating feline genetics in detail. In England, Alex Jeffreys developed "genetic fingerprinting," which can identify an individual from a sample of DNA from any body tissue.

This can be used in cats, as in humans, to investigate paternity. Because pedigreed cats often have similar DNA, however, especially in the rarer breeds, genetic profiling can only exclude a sire, not identify one.

In reality, the vast majority of cat matings remain random, and selection for survival of the fittest remains the most powerful influence on the genetic future of the domestic cat. Increasingly, however, advances in genetics will be used to monitor exactly what is happening.