The Lutino is a sex-linked mutation. It is one of the most common and most easily recognisable mutations across the parrot species.
The Lutino mutation governs the production of black, grey and brown pigments (grey-family pigments). The Lutino mutation doesn’t delete all grey-family pigments, it acts more like a sieve in some species including the cockatiel. This is why when the Lutino mutation is combined with Cinnamon, some of the cinnamon or brown pigments still come through. In fact, some Lutino cocks produce a cinnamon-like wash or overlay on their back and wings when they mature. This does not mean that the bird contains cinnamon and in fact, if you compare a Lutino with a mature cinnamon-like wash with a Lutino Cinnamon, you can clearly see that the difference. The Lutino Cinnamon has a much darker cinnamon colour.
The Albino gene in mammals is similar to the Lutino gene; however no single gene can remove both grey family and yellow family (yellow, orange and red) pigments. To produce an Albino in parrots you need to combine the Lutino gene which removes grey family pigments with the Blue gene to remove the yellow family pigments. The Blue gene in the cockatiel is called the Whiteface mutation. Both the Whiteface and Lutino mutations are combined in the cockatiel to produce an Albino.
Being devoid of grey-family pigments, a Lutino can ONLY show white, yellow, orange and red. All dark body areas (feet, nails, and beak) revert to a pinkish-white colour. As stated above, the Lutino can show some cinnamon-like colour, however this looks more like a dirty Lutino. A lot of people confuse a Pied or Pearl-Pied or Cinnamon-Pearl-Pied as being a Lutino. A good rule of thumb is if your bird shows ANY grey/brown/black markings or coloured areas then it is NOT a Lutino.
The Lutino also has red to dark ruby eyes. This is not always obvious as when the birds get older their eyes appear dark/black until they are caught in the right light or a torch is shone in their eyes. This can then confuse people as a Lutino and a 100% reverse Pied (Pied that is covered in yellow/white marking that it shows no colour/black/grey) will look similar until a light source is used. This can even be more confusing with a 100% reverse Cinnamon Pied as the Cinnamon mutation also has a red to ruby eye ring.
It is quite common for Lutino cockatiels to have a bald patch behind their crest. This is a fault due to previous inbreeding of the mutation and no Lutino or any other mutation should have a bald or thin patch. However, most Lutino cockatiels still have a bald or thin patch on the top of their head behind their crest. When sourcing your Lutino stock, make sure you source good quality Lutino birds. Some thin or bald patches are only noticeable in young birds at 3-4 weeks of age that are not fully feathered as when the feathers behind the crest grow, they will usually cover up most thin patches. This is true with not only the Lutino mutation, but other mutations as well so make sure when you are sourcing birds to put to a Lutino that they have fully covered heads.