Cat genetics

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Blue-eyed cats with white fur have a high incidence of genetic deafness. WhiteCat.jpg
Blue-eyed cats with white fur have a high incidence of genetic deafness.

Cat genetics describes the study of inheritance as it occurs in domestic cats. In feline husbandry it can predict established traits (phenotypes) of the offspring of particular crosses. In medical genetics, cat models are occasionally used to discover the function of homologous human disease genes.

The domesticated cat and its closest wild ancestor are both diploid organisms that possess 38 chromosomes [2] and roughly 20,000 genes. [3] About 250 heritable genetic disorders have been identified in cats, many similar to human inborn errors. [4] The high level of similarity among the metabolisms of mammals allows many of these feline diseases to be diagnosed using genetic tests that were originally developed for use in humans, as well as the use of cats in the study of the human diseases. [5] [6]

An example of a mutation that is shared among all felines, including the big cats, is a mutant chemosensor in their taste buds that prevents them from tasting sweetness, which may explain their indifference to fruits, berries, and other sugary foods. [7] In some breeds of cats congenital sensorineural deafness is very common, with most white cats (but not albinos) being affected, particularly if they also have blue eyes. [1] The gene responsible for this defect is the KIT gene and the disease is studied in the hope that it may shed light on the causes of hereditary deafness in humans. [8] Mutations in this gene also causes white spotting. [9]

Since a large variety of coat patterns exist within the various cat breeds, the cat is an excellent animal to study the coat genetics of hair growth and coloration. [10] Several genes interact to produce cats' hair color and coat patterns. Different combinations of these genes give different phenotypes. For example, the enzyme tyrosinase is needed to produce the dark pigment melanin and Burmese cats have a mutant form that is only active at low temperatures, resulting in color appearing only on the cooler ears, tail and paws. [11] A completely inactive gene for tyrosinase is found in albino cats, which therefore lack all pigment. [12] Hair length is determined by the gene for fibroblast growth factor 5, with inactive copies of this gene causing long hair. [13]

The Cat Genome Project, sponsored by the Laboratory of Genomic Diversity at the U.S. National Cancer Institute Frederick Cancer Research and Development Center in Frederick, Maryland, aims to help the development of the cat as an animal model for human hereditary and infectious diseases, as well as contributing to the understanding of the evolution of mammals. [6] This effort led to the publication in 2007 of an initial draft of the genome of an Abyssinian cat called Cinnamon. [3] The existence of a draft genome has led to the discovery of several cat disease genes, [3] and even allowed the development of cat genetic fingerprinting for use in forensics. [14]

See also

Related Research Articles

<span class="mw-page-title-main">Autosome</span> Any chromosome other than a sex chromosome

An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal pairs, which may have different structures. The DNA in autosomes is collectively known as atDNA or auDNA.

<span class="mw-page-title-main">Phenotype</span> Composite of the organisms observable characteristics or traits

In genetics, the phenotype is the set of observable characteristics or traits of an organism. The term covers the organism's morphology, its developmental processes, its biochemical and physiological properties, its behavior, and the products of behavior. An organism's phenotype results from two basic factors: the expression of an organism's genetic code and the influence of environmental factors. Both factors may interact, further affecting the phenotype. When two or more clearly different phenotypes exist in the same population of a species, the species is called polymorphic. A well-documented example of polymorphism is Labrador Retriever coloring; while the coat color depends on many genes, it is clearly seen in the environment as yellow, black, and brown. Richard Dawkins in 1978 and then again in his 1982 book The Extended Phenotype suggested that one can regard bird nests and other built structures such as caddisfly larva cases and beaver dams as "extended phenotypes".

<span class="mw-page-title-main">Bicolor cat</span> Cat having fur of two colors

A bicolor cat or [color]-and-white cat is a cat with white fur combined with fur of some other color, for example solid black, tabby, or colorpointed. There are various patterns of bicolor cat. These range from the Van-patterned through to solid color with a throat locket or medallion. Bicolor coats are found in many cat breeds, as well as being common in domestic longhair and domestic shorthair cats.

<span class="mw-page-title-main">Dominance (genetics)</span> One gene variant masking the effect of another in the other copy of the gene

In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and the second is called recessive. This state of having two different variants of the same gene on each chromosome is originally caused by a mutation in one of the genes, either new or inherited. The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes (autosomes) and their associated traits, while those on sex chromosomes (allosomes) are termed X-linked dominant, X-linked recessive or Y-linked; these have an inheritance and presentation pattern that depends on the sex of both the parent and the child. Since there is only one copy of the Y chromosome, Y-linked traits cannot be dominant or recessive. Additionally, there are other forms of dominance, such as incomplete dominance, in which a gene variant has a partial effect compared to when it is present on both chromosomes, and co-dominance, in which different variants on each chromosome both show their associated traits.

<span class="mw-page-title-main">Cat coat genetics</span> Genetics responsible for the appearance of a cats fur

Cat coat genetics determine the coloration, pattern, length, and texture of feline fur. The variations among cat coats are physical properties and should not be confused with cat breeds. A cat may display the coat of a certain breed without actually being that breed. For example, a Neva Masquerade could wear point coloration, the stereotypical coat of a Siamese.

<span class="mw-page-title-main">Waardenburg syndrome</span> Genetic condition involving hearing loss and depigmentation

Waardenburg syndrome is a group of rare genetic conditions characterised by at least some degree of congenital hearing loss and pigmentation deficiencies, which can include bright blue eyes, a white forelock or patches of light skin. These basic features constitute type 2 of the condition; in type 1, there is also a wider gap between the inner corners of the eyes called telecanthus, or dystopia canthorum. In type 3, which is rare, the arms and hands are also malformed, with permanent finger contractures or fused fingers, while in type 4, the person also has Hirschsprung's disease. There also exist at least two types that can result in central nervous system (CNS) symptoms such as developmental delay and muscle tone abnormalities.

<span class="mw-page-title-main">Non-Mendelian inheritance</span> Type of pattern of inheritance

Non-Mendelian inheritance is any pattern in which traits do not segregate in accordance with Mendel's laws. These laws describe the inheritance of traits linked to single genes on chromosomes in the nucleus. In Mendelian inheritance, each parent contributes one of two possible alleles for a trait. If the genotypes of both parents in a genetic cross are known, Mendel's laws can be used to determine the distribution of phenotypes expected for the population of offspring. There are several situations in which the proportions of phenotypes observed in the progeny do not match the predicted values.

<span class="mw-page-title-main">Medical genetics</span> Medicine focused on hereditary disorders

Medical genetics is the branch of medicine that involves the diagnosis and management of hereditary disorders. Medical genetics differs from human genetics in that human genetics is a field of scientific research that may or may not apply to medicine, while medical genetics refers to the application of genetics to medical care. For example, research on the causes and inheritance of genetic disorders would be considered within both human genetics and medical genetics, while the diagnosis, management, and counselling people with genetic disorders would be considered part of medical genetics.

<span class="mw-page-title-main">Melanophilin</span> Protein-coding gene in the species Homo sapiens

Melanophilin is a carrier protein which in humans is encoded by the MLPH gene. Several alternatively spliced transcript variants of this gene have been described, but the full-length nature of some of these variants has not been determined.

<span class="mw-page-title-main">Labrador Retriever coat colour genetics</span> Genetics behind Labrador Retriever coat colour

The genetic basis of coat colour in the Labrador Retriever has been found to depend on several distinct genes. The interplay among these genes is used as an example of epistasis.

<span class="mw-page-title-main">TYRP1</span> Enzyme

Tyrosinase-related protein 1, also known as TYRP1, is an intermembrane enzyme which in humans is encoded by the TYRP1 gene.

<span class="mw-page-title-main">STRC</span> Protein-coding gene in the species Homo sapiens

Stereocilin is a protein that in humans is encoded by the STRC gene.

<span class="mw-page-title-main">MCOLN3</span> Protein-coding gene in the species Homo sapiens

Mucolipin-3 also known as TRPML3 is a protein that in humans is encoded by the MCOLN3 gene. It is a member of the small family of the TRPML channels, a subgroup of the large protein family of TRP ion channels.

Oculocutaneous albinism type I or type 1A is an autosomal recessive skin disease. This subtype of oculocutaneous albinism is caused when the gene for tyrosinase does not function properly.

<span class="mw-page-title-main">Gene redundancy</span>

Gene redundancy is the existence of multiple genes in the genome of an organism that perform the same function. Gene redundancy can result from gene duplication. Such duplication events are responsible for many sets of paralogous genes. When an individual gene in such a set is disrupted by mutation or targeted knockout, there can be little effect on phenotype as a result of gene redundancy, whereas the effect is large for the knockout of a gene with only one copy. Gene knockout is a method utilized in some studies aiming to characterize the maintenance and fitness effects functional overlap.

<span class="mw-page-title-main">Congenital sensorineural deafness in cats</span> High rates of congenital deafness in white cats with light-coloured eyes

Congenital sensorineural deafness occurs commonly in domestic cats with a white coat. It is a congenital deafness caused by a degeneration of the inner ear. Deafness is far more common in white cats than in those with other coat colours.

<span class="mw-page-title-main">Dominant white</span> Horse coat color and its genetics

Dominant white (W) is a group of genetically related coat color alleles on the KIT gene of the horse, best known for producing an all-white coat, but also able to produce various forms of white spotting, as well as bold white markings. Prior to the discovery of the W allelic series, many of these patterns were described by the term sabino, which is still used by some breed registries.

<span class="mw-page-title-main">Stephen D. M. Brown</span>

Steve David Macleod Brown is director of the Medical Research Council (MRC) Mammalian Genetics Unit, MRC Harwell at Harwell Science and Innovation Campus, Oxfordshire, a research centre on mouse genetics. In addition, he leads the Genetics and Pathobiology of Deafness research group.

<span class="mw-page-title-main">Domestication of the cat</span> Evolutionary origins of domesticated cats

The domestic cat originated from Near-Eastern and Egyptian populations of the African wildcat, Felis sylvestris lybica. The family Felidae, to which all living feline species belong, arose about ten to eleven million years ago and is divided into eight major phylogenetic lineages. The Felis lineage in particular is the lineage that the domestic cat is a member of. A number of investigations have shown that all domestic varieties of cats come from a single species of the Felis lineage, Felis catus. Variations of this lineage are found all over the world, and until recently scientists have had a hard time pinning down exactly which region gave rise to modern domestic cat breeds. Scientists believed that it was not just one incident that led to the domesticated cat but multiple, independent incidents at different places that led to these breeds. More complications arose from the fact that the wildcat population as a whole is very widespread and very similar to one another. These variations of wildcat can and will interbreed freely with one another when in close contact, further blurring the lines between taxa. Recent DNA studies, advancement in genetic technologies, and a better understanding of DNA and genetics as a whole has helped make discoveries in the evolutionary history of the domestic cat. Archaeological evidence has documented earlier dates of domestication than formerly believed.

The agouti gene, the Agouti-signaling protein (ASIP) is responsible for variations in color in many species. Agouti works with extension to regulate the color of melanin which is produced in hairs. The agouti protein causes red to yellow pheomelanin to be produced, while the competing molecule α-MSH signals production of brown to black eumelanin. In wildtype mice, alternating cycles of agouti and α-MSH production cause agouti coloration. Each hair has bands of yellow which grew during agouti production, and black which grew during α-MSH production. Wildtype mice also have light-colored bellies. The hairs there are a creamy color the whole length because the agouti protein was produced the whole time the hairs were growing.

References

  1. 1 2 Strain GM (1996). "Aetiology, prevalence and diagnosis of deafness in dogs and cats". Br. Vet. J. 152 (1): 17–36. doi:10.1016/S0007-1935(96)80083-2. PMID   8634862.
  2. Nie W, Wang J, O'Brien PC (2002). "The genome phylogeny of domestic cat, red panda and five mustelid species revealed by comparative chromosome painting and G-banding". Chromosome Res. 10 (3): 209–22. doi:10.1023/A:1015292005631. PMID   12067210. S2CID   9660694.
  3. 1 2 3 Pontius JU, Mullikin JC, Smith DR, et al. (2007). "Initial sequence and comparative analysis of the cat genome". Genome Res. 17 (11): 1675–89. doi:10.1101/gr.6380007. PMC   2045150 . PMID   17975172.
  4. O'Brien SJ, Johnson W, Driscoll C, Pontius J, Pecon-Slattery J, Menotti-Raymond M (2008). "State of cat genomics". Trends Genet. 24 (6): 268–79. doi:10.1016/j.tig.2008.03.004. PMC   7126825 . PMID   18471926.
  5. Sewell AC, Haskins ME, Giger U (2007). "Inherited metabolic disease in companion animals: searching for nature's mistakes". Vet. J. 174 (2): 252–9. doi:10.1016/j.tvjl.2006.08.017. PMC   3132193 . PMID   17085062.
  6. 1 2 O'Brien SJ, Menotti-Raymond M, Murphy WJ, Yuhki N (2002). "The Feline Genome Project". Annu. Rev. Genet. 36: 657–86. doi:10.1146/annurev.genet.36.060602.145553. PMID   12359739.
  7. Li, Xia; Li, Weihua; Wang, Hong; Cao, Jie; Maehashi, Kenji; Huang, Liquan; Bachmanov, Alexander A.; Reed, Danielle R.; et al. (2005). "Pseudogenization of a Sweet-Receptor Gene Accounts for Cats' Indifference toward Sugar". PLOS Genetics. Public Library of Science. 1 (1): 27–35. doi: 10.1371/journal.pgen.0010003 . PMC   1183522 . PMID   16103917.
  8. Saada AA; Niparko JK; Ryugo DK (1996). "Morphological changes in the cochlear nucleus of congenitally deaf white cats". Brain Res. 736 (1–2): 315–28. doi:10.1016/0006-8993(96)00719-6. PMID   8930338. S2CID   10409257.
  9. Montague, M. J.; Li, G.; Gandolfi, B.; Khan, R.; Aken, B. L.; Searle, S. M.; Minx, P.; Hillier, L. W.; Koboldt, D. C.; Davis, B. W.; Driscoll, C. A. (2014). "Comparative analysis of the domestic cat genome reveals genetic signatures underlying feline biology and domestication". Proceedings of the National Academy of Sciences. 111 (48): 17230–17235. Bibcode:2014PNAS..11117230M. doi: 10.1073/pnas.1410083111 . PMC   4260561 . PMID   25385592.
  10. Robinson, Roy; Vella, Carolyn M.; Lorraine Shelton; McGonagle, John J.; Carolyne Vella (1999). Robinson's genetics for cat breeders and veterinarians. Oxford: Butterworth-Heinemann. ISBN   0-7506-4069-3.
  11. Lyons LA, Imes DL, Rah HC, Grahn RA (2005). "Tyrosinase mutations associated with Siamese and Burmese patterns in the domestic cat (Felis catus)". Anim. Genet. 36 (2): 119–26. doi: 10.1111/j.1365-2052.2005.01253.x . PMID   15771720.
  12. Imes DL, Geary LA, Grahn RA, Lyons LA (2006). "Albinism in the domestic cat (Felis catus) is associated with a tyrosinase (TYR) mutation". Anim. Genet. 37 (2): 175–8. doi:10.1111/j.1365-2052.2005.01409.x. PMC   1464423 . PMID   16573534.
  13. Kehler JS, David VA, Schäffer AA (2007). "Four independent mutations in the feline fibroblast growth factor 5 gene determine the long-haired phenotype in domestic cats". J. Hered. 98 (6): 555–66. doi:10.1093/jhered/esm072. PMC   3756544 . PMID   17767004.
  14. Menotti-Raymond M, David VA, Stephens JC, Lyons LA, O'Brien SJ (1997). "Genetic individualization of domestic cats using feline STR loci for forensic applications". J. Forensic Sci. 42 (6): 1039–51. doi:10.1520/JFS14258J. PMID   9397545.