Are bicolor cats rare, friendly, hypoallergenic?

Tuxedo cats are bicolor cats. This is my darling deceased female. Image: MikeB

Bicolor cats are cats with a coat of two (as in 'bi') colors: white and another colour such as black or ginger. And the 'other colour' can have tabby markings. 

They can be moggies (random-bred cats) or purebred, pedigree cats. It does not matter which. They are common and therefore not rare. Neither are they hypoallergenic but they are friendly if they've been socialised properly and treated well.

No domestic cat is hypoallergenic as the Fel D1 allergen is produced by all domestic cats. Purina LiveClear works pretty well to make a cat acceptable to a person allergic to cats.

'Hypoallergenic' means not producing an allergic reaction in people. About 10% of people are allergic to cats.

The white fur in bicolor cats is caused by the presence of the piebald aka white spotting gene, which affects the migration of pigment producing cells (melanocytes) in the skin during the development of the embryo. 

Where there are no melanocytes there is no melanin in the hair strands. White fur does not contain pigment namely melanin.

It is white because the light from sun or room light passes through it. White light is a mixture of all the colours of the rainbow.

Melanin is a brown/black. If it is diluted, black becomes blue grey and red becomes cream and so on.

The experts rate bicolor cats from 1 to 10 depending on the amount of white fur. Level 1 is black and no white fur while level 10 is all-white. The cat in the picture is about level 4.

If you have a question, ask in a comment and I'll be pleased to respond. I always check comments as I get so few! :)

Level 9 bicolor Cornish Rex. Image in the public domain.