Why r some white cats deaf?

Question

i know it has nothing to do with the colour of the eyes as any coloured eyes can b deaf,i want to know the physical reason,is there a defect in the ears and/or what is it?why are they deaf and can they be cured?

Answer 1

There are different genes that cause white colour in cats.  One of those genes causes blue eyes and can cause deafness as a side-effect.

The gene linked to deafness is the "dominant white" gene.  As well as affecting fur colour and eye colour it disrupts the formation of the cochlea (the "hearing structure" in the ears) which results in deafness.  The eye and ear are close together so you can see how a mutation that affects the way the eyes form will also affect the way the ears form.  Because the cochlea hasn't developed correctly right from the embryo stage, the deafness can't be cured.

If the white cat has orange/green/hazel eyes, this is an indication that the cochlea has developed normally.  If the cat has one eye blue and the other is orange/green/hazel then the cochlea on the side of the blue eye will have been disrupted and the cat deaf on that side.

There is another gene that causes white and it is known as white spotting, but can sometimes result in the cat being completely white.  This gene is less likely to cause deafness (often kittens with the white spotting gene have some coloured fur on the top of their head known as a "kitten cap" - this disappears later on but is a clue about which gene the cat has, cats with "dominant white" don't have a kitten cap as babies).

15-40% of pure white cats have one or two blue-eyes.

Of those white cats with one or two blue eyes, 60-80% are deaf; 20-40% have normal hearing

30-40% of the pure white cats had one blue eye and were deaf while 60-70% had one blue eye and normal hearing.

Those are cats with the dominant white gene that disrupts the development of the cochlear.

60-80% of white cats have both eyes of other colors (e.g. orange, green) and only 10- 20% were deaf and 80-90% have normal hearing.

These are cats withe the white spotting gene that usually doesn't affect the ear.

Answer 2

The genes that carry the blue eye/white fur trait can cause deafness.

"Deafness is caused by an absence of a cell layer in the inner ear that originates from the same stem cells... In odd-eyed white cats, the ear on the blue-eyed side may be deaf, but the one on the orange-eyed side usually has normal hearing. Not all blue-eyed whites will be deaf since there are several different genes causing the same physical attributes (whiteness, blue-eyedness) so it all depends on the cat's genotype (its genetic make-up) not its phenotype (its physical appearance)."

The deafness is hereditary and incurable,