A (lengthy) article on BP Gentics

[RandyRemington]

Thanks!

So what is the definition of homozygous lethal? It was once suggested to me that the definition could be as broad as not being capable of reproducing. Does the woma/pearl qualify? Maybe there is a better term as the "lethal" part certainly seems to imply death and not just not being capable of it's biological imperative.

I do believe that at one point there was a post by someone in a large spider breeding camp that the spider X spider clutches didn't tend to slug any more than other ball pythons. I don't think any actual numbers or sample size was given. I still wouldn't rule it out as even normal ball pythons have been known to slug at rates that could compare to a homozygous lethal situation. But if you look at published large samples of non spider X non spider breedings like on Ralph Davis' breeding records pages it does seem the "normal" rate of slugs could be misleading as it's more often an all or nothing thing (some clutches totally bad but many others totally good rather than a steady high slug rate in all clutches). But I still question if homozygous spider eggs didn't hatch if it would be dismissed as a normal slug rate. It would take a pretty good sample size of spider X spider breedings and careful records to "prove" a trend if homozygous spider eggs don't hatch.

I also wonder if the homozygous spiders did hatch but where less perfect in some way like the pearl if we would hear about it. The pearl was the first reported cb white ball python so was very exciting to the community but unfortunately the lesson learned may have been to be much less forthcoming with information about any potential problems. If there are a couple similar projects now they might be sold for years before the details are publicly disclosed.

[Mendel's Balls]

From Cornell University Dept. of Animal Science:

embryonic lethal genotype: Genotype whose expression results in the prenatal death of the individual possessing it.

lethal genotype: Genotype whose expression results in the death of the individual possessing it.

Note lethal alleles or genotypes just cause a premature death. That death does not need to occur during embryonic development or childhood. Huntington disease typically causes a slow and sad decline to death in middle age. You only need one copy of this allele to get the diease. Hence, its classified as a autosomal dominant disorder.