Is it true that white blue -eyed cats are deaf?

It has long been believed that deafness is characteristic of cats with certain external features. Most often, white wool and blue eyes appear in this context. We checked whether the overwhelming number of such pets are deaf.

More Charles Darwin in his "The origin of species" He wrote: “White cats with blue eyes are usually deaf; But, as Mr. Tate recently testified, this feature is characteristic only of cats. ” Familiar with the works of the British Friedrich Engels in "Dialectics of nature" He also noted that "completely white cats with blue eyes always or almost always turn out to be deaf." Similar statements are often found in social networks.

As noted scientistsThe deafness of white blue -eyed cats (along with Dalmatins) is the most famous example of possessing a similar property in the animal world. It is obvious that experts in genetics are able to give the answer to the question of the presence and degree of dependence between such different signs. We turn to them.

To begin with, it should be noted that albinos is often mistakenly called any white cats. Meanwhile albinism - This is a hereditary disease in which there is a complete absence of color or pigmentation. In order for the kitten to be born an albinos, both of his parents must have a genetic predisposition to this. The wool of the albino cat may seem white, but upon closer examination, a number of differences are found.

In particular, in a real white cat, the eyes can have almost any common color, as well as heterochrome (each eye of one color). But the eyes of albino cats have a very limited set of shades due to the complete lack of pigmentation. They can be either pale blue, or pinkish, or pinkish-blue.

The case that we consider concerns cats with real white wool, since it is in their case that Genetic dependence. It is associated with the presence of a dominant allele (gene form) W, responsible for the white color of the animal’s hair. If at least one of the alleles in the animal’s genotype is dominant mutant W, then the body cells lose their ability to organize and do not produce pigment, and the cat, with rare exceptions, remains unpainted, that is, white until the end of life.

For us, it is much more important that a dominant white color can violate the formation of not only future pigment, but also nearby cells responsible for the formation of other structures. So, the blue color of the eyes occurs due to the lack of pigment and the complete absence of a tapetum (layer of the vascular membrane) in the eyes of the animal, and deafness-due to the lack of pigment in the curtain organ (part of the sound-acceptance apparatus). The result is blue -eyed (one or both eyes) and deaf cats with a mutant allele W.

So, we understood the nature of the connection between the color of the wool, blue -eyed and deafness, but what does statistics say? What is the probability that these three signs will coincide? There are at least three classic research On this topic, conducted by Western scientists (Bosher and Hallpike, 1965; Mair, 1973; Bergsma and Brown, 1971) in total on 256 cats. If we generalize, the prevalence of deafness was from 65% to 85% in cats with two blue eyes, 39–40% in cats with one blue eye and from 17% to 22% in cats without blue eyes. Another study The prevalence of deafness in 84 purebred white cats, belonging to ten famous breeds, gave the following results: 9.5% of one -sidedly deaf and 10.7% bilaterally deaf, that is, 20.2% of cats with deafness. How many blue -eyed were not reported among these cats.

Thus, according to today's well-known studies, the percentage of white blue-eyed cats with congenital deafness is really high, but the characteristic of “everything” or “almost everything” here is still inappropriate. We also note that among cats-albinos, which are considered “white”, such a genetic deviation is not common. If we talk about cats in general, then, according to research 1991, white cats make up about 5.7% of the total population and 15% of them have blue eyes.

The image on the cover: Pixabay.

Half truth

What do our verdicts mean?

Read on the topic:

1. Deafness in Blue-Eyed White Cats: The Uphill Road to Solving Polygenic Disorders
2. The Genetics of Deafness in Domestic Animals
3. Analysis of hereditary patterns on the genes of Felis catus cats