Pretty sure I read in fact they are technically NOT albino
Here is one explanation
Let me start by saying there is no such thing as a "True Albino" cockatiel. What we call an albino cockatiel only has the phenotype (appearance) of an albino (all white feathers, pink feet, red eyes and no cheek patch). The reason it appears this way is that it is really a combination of the sex-linked Lutino mutation and the autosomal recessive Whiteface mutation. Lutino is a mutation which has affected the melanin pigment in such a way that no melanin (grey or brown coloration) is produced. Thus, a Lutino is a white or yellow bird with red eyes and an orange cheekpatch. Whiteface, however, affects the lipochrome (yellow and orange) pigment in such a way that no lipochrome is produced. Without either melanin or lipochrome, the resulting cockatiel lacks in any color and appears to be an albino. What's the difference? There's a big difference where genetic determination is concerned.
But again does this apply to all white birds thus chickens? Who knows
The thing is, there's a difference between a form of albinism (still an albino) and a bird lacking any colors at all and being as you say a "true albino".
I have only bred snakes so I'll use that example just cause I'm better informed with it and may not be getting something.
A snake can have genes to lack red, or black,or yellow, lack both red and black, or yellow and black, or lack red black and yellow.
Each gene expressed to fully subtract one color from the appearance of the snake is in fact a form of albinism. Thus you would not be technically wrong in calling any of the above snakes an albino, even though it still has some colors (or not) you would just be over simplifying.
No combination of these albinisms is actually called a "true albino" by breeders because you have to stack 4+ known mutations to get a truly pigment-less snake (and that's just the known mutations!), and if they happen to carry genes for non-albinism phenotype altering genes you still get funky colors creeping in.
Once I get into allelic and stacking expression genes I can understand better than I can converse about them, some things you can't have happen at the same time without the individual dying or you can't see expressed unless another mutation is present to activate/reveal it, etc.
What you just described to me in lutinos sounds like exactly what a form of albinism is, though the sex linked part is very interesting to me though not described in detail so I can't say anything to it as I haven't seen such genes in snakes.
So a cockatiel lacking grey as a lutino would to my snake keeping terms be amelanistic (lacking only black), a form of albinism, but not axanthic and thus still have yellow. Just my own point of view from having to track stacking genes in snakes and their phenotype outcomes.
So what is the genetic determination difference causing this to
not be a form of albinism then?
As described, this is a mutation which removes a pigment which breeds true and thus is genetic. To me, sex linked, restricted to one pigment in a multi-pigmented animal, or not, that's what an albino is.
Understand what I mean? If I'm missing something specific to birds or something I'd love to learn more about it.
Cheers,
Jessie
