The cat, like other mammals such as humans and mice, has been estimated to have approximately 80,000 genes in its genome. These genes are scattered over 38 chromosomes in the cat and are made up of of DNA(deoxyribonucleic acid). Four chemical bases, simply known as A,T,C, and G, are randomly strung together many times over to form a precise DNA sentence or sequence which is characteristic of a particular gene. It is this genetic blueprint that instructs the cells to make a certain gene product and collectively these products form the tissues, organs, bones, teeth, hair etc that make up the cat. A change in the spelling of the DNA alphabet of a gene may result in a disease causing gene product such as that causing muscular dystrophy to be formed, or a harmless gene product such as one which determines brown hair pigmentation instead of black.
Although the number of chromosomes varies between cats, humans and mice, almost every cell that makes up these different species contains a set of gene-carrying chromosomes. Research to date indicates that many millions of years ago cats, humans and mice probably shared a common mammalian ancestor and that if the chromosome address of an individual gene is known in one of these species, it can be used to predict where this gene may reside in another with a high degree of accuracy.
In recent years, scientists have developed the technology, known as molecular biology, to decode the DNA sequence of individual genes. This ability has allowed a particular gene or genes responsible for certain characteristics or diseases in many species to be identified. Indeed, certain genetic discoveries in mice have lead to the identification of the precise genetic mutations responsible for recessive red hair, hairlessness and pigment loss(white spotting/piebaldism)in humans. To date there are at least five genes identified in mice and humans(including dominant white and albinism) that have incurred mutations which result in varying degrees of white hair formation and in some cases, deafness. These genes are good candidates for understanding the genetic basis of the wide variety of white markings that can be seen on pedigreed cats ranging from the white paws on the Birman, the solid white-coloured Persian or British, to the unwelcome random white spotting that may occur on some of the coats of 'non-white' pedigreed cats. Identifying the precise 'white-gene equivalents' in cats should also give us a better understanding of the documented association with some white-coloured cats and deafness.
Interestingly, using the so-called New Genetics', scientists have been able to decode the precise genetic mutations responsible for mice that display the shortened or absent tails, waved hair texture as well as himalayan, agouti and silver coat colours. These exciting discoveries in mice may provide valuable clues in understanding the exact genes responsible for these appearances in cats such as Japanese Bobtail, Manx, Rex Breeds and Siamese as well as cats that exhibit golden vs chinchilla or brown vs silver tabby coat colours.
Besides providing valuable clues for feline appearance, the Feline Genome Project promises to provide valuable insight into the inherited diseases of the cat and their associated health problems. Some of the genes responsible for diseases such as cardiomyopathy, kidney disease, diabetes and cancer, as well as conditions such as cleft palate and obesity have now been identified in the mouse and/or human. This work has now progressed to the extent that there are approximately 500 inherited diseases that can be diagnosed in human beings by DNA analysis in the laboratory. In general, DNA is harvested from a small sample of blood but it can also be extracted from a tiny amount of tissue such as a hair follicle or an archival tissue sample such as that found on a pathology slide.
The understanding of the exact DNA sequence and chromosome location of the genes that make up the cat genome will greatly enhance our ability to breed healthier and better cats. It will enable laboratory tests to be developed for screening our breeding stock for the presence of potentially harmful genetic mutations before they are entered into the breeding program. In addition, it will enable the origin and the precise relatedness of the cat breeds to be determined as well as exploring issues such as doubtful paternity and level of inbreeding. The latter is a very important issue because as cat breeders strive for ideal breed characteristics, the feline gene pool may be reduced to such an extent that a breed may be eventually threatened with extinction. Finally, mapping and identifying the genes that make the cat has the potential to lead to the development of improved veterinary treatment and health management of cats because knowing the exact underlying genetic cause should enable early lifestyle changes to be made and/or efficient tailor-made therapies to be developed.
In conclusion, a huge International consortium of scientists is currently busily decoding the DNA alphabet of the genes that make up the entire human genome. This work has been extended to many other species including the mouse and cat. Although identifying the DNA sequence of the estimated 80,000 genes which make the cat has begun, this work is in its infancy and would greatly benefit by the support of cat fanciers and scientists worldwide. This is something we can all participate in without putting any cat's life at risk by providing careful observation, accurate pedigrees, access to veterinary records and fundraising.
NOTE: The Feline Genome Project website can be visited via the Cat Fanciers Association site (http://www.cfainc.org/exhibitors/feline-genome-project.html). More information about the genes in mice, humans and cats mentioned in this article can be found by searching the PubMed site (http://www.ncbi.nlm.nih.gov/PubMed) using keywords of interest.
