A T-negative albino lacks black pigment because a defective tyrosinase enzyme prevents black pigment from forming. A T-positive albino lacks black pigment because a defect in an unknown enzyme (other than the tyrosinase enzyme) prevents black pigment from forming.

I asked Dave Barker several years ago whether any boas or pythons had actually been tested for tyrosinase activity. He said no, and I have not heard different since then.

There are four possibilities:
1. The Kahl strain of albino is T-negative, and the Sharp strain is T-positive.
2. The Kahl strain of albino is T-positive, and the Sharp strain is T-negative.
3. Both strains are T-positive.
4. Both strains are T-negative.

We do not know which possibility is correct. However, as far as I know, there is only one gene locus that produces the tyrosinase enzyme. As the Kahl and Sharp strains are not compatible, there is essentially no chance that both strains are T-neg.

In other words, calling both the Kahl and Sharp strains of albinos tyrosinase negative albinos is almost certainly incorrect.

The mutants that people call T-positive albinos have some black pigment. They could produce the observed effect because of a partially functional tyrosinase enzyme or because of a nonfunctional or partially functional enzyme that has not been identified yet. For what it's worth, Siamese cats are lighter than normal cats because Siamese cats have a partly functional tyrosinase enzyme.

I'd like to see the Kahl and Sharp albinos given unique names. I'd also like to see the two anerythristics, the two caramels, and the various "T-positive albinos" given unique names. This would eliminate a lot of confusion. Anyone who can persuade the boa breeders to do this would have my unbounded admiration.

Paul Hollander

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