Cat genetics

Blue-eyed cats with white fur have a high incidence of genetic deafness.[1]

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 deafness is very common, with most white cats (but not albinos) being affected, particularly if they also have blue eyes.[1] The genes responsible for this defect are unknown, but the disease is studied in the hope that it may shed light on the causes of hereditary deafness in humans.[8]

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.[9] 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.[10] A completely inactive gene for tyrosinase is found in albino cats, which therefore lack all pigment.[11] Hair length is determined by the gene for fibroblast growth factor 5, with inactive copies of this gene causing long hair.[12]

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.[13]

See also

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; Wang; O'Brien; Fu; Ying; Ferguson-Smith; Yang (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.
  3. 1 2 3 Pontius JU, Mullikin JC, Smith DR, JU; Mullikin, JC; Smith, DR; Agencourt Sequencing, Team; Lindblad-Toh, K; Gnerre, S; Clamp, M; Chang, J; Stephens, R; Neelam; Volfovsky, N; Schäffer, AA; Agarwala, R; Narfström, K; Murphy, WJ; Giger, U; Roca, AL; Antunes, A; Menotti-Raymond, M; Yuhki, N; Pecon-Slattery, J; Johnson, WE; Bourque, G; Tesler, G; Nisc Comparative Sequencing; O'Brien (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; Johnson; Driscoll; Pontius; Pecon-Slattery; Menotti-Raymond (2008). "State of cat genomics". Trends Genet. 24 (6): 268–79. doi:10.1016/j.tig.2008.03.004. PMID 18471926.
  5. ↑ Sewell AC, Haskins ME, Giger U; Haskins; Giger (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; Menotti-Raymond; Murphy; Yuhki (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; Niparko; Ryugo (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.
  9. ↑ 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.
  10. ↑ Lyons LA, Imes DL, Rah HC, Grahn RA; Imes; Rah; Grahn (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.
  11. ↑ Imes DL, Geary LA, Grahn RA, Lyons LA; Geary; Grahn; Lyons (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.
  12. ↑ Kehler JS, David VA, Schäffer AA; David; Schäffer; Bajema; Eizirik; Ryugo; Hannah; O'Brien; Menotti-Raymond (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.
  13. ↑ Menotti-Raymond M, David VA, Stephens JC, Lyons LA, O'Brien SJ; David; Stephens; Lyons; O'Brien (1997). "Genetic individualization of domestic cats using feline STR loci for forensic applications". J. Forensic Sci. 42 (6): 1039–51. PMID 9397545.
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