Homozygous Dominant Genes

[rigomez4]

I have read that some people believe homozygous dominant genes may result in a lethal gene combination. All I have read use a spider x spider cross (homozygous spider) as an example. I was wondering if it holds true for,

pinstripe x pinstripe (homozygous pinstripe)
spinner (spider/pinstripe) x spider (homozygous spider)
spinner (spider/pinstripe) x pinstripe (homozygous pinstripe)

I just have not read anything on the potential lethal gene in these combinations. Thanks.

[Jessica Loesch]

No one knows for sure.

[paulh]

Homozygous codominant mutant genes MAY result in a lethal gene combination. Homozygous recessive mutant genes also MAY result in a lethal gene combination. They are not required to result in a lethal gene combination.

A lethal dominant gene is lethal when there is one mutant gene in the gene pair. Such mutant genes do not survive to a second generation except in rare circumstances.

As far as I know, homozygous pinstripe is not lethal.

As Jessica wrote, nobody is certain about homozygous spider. Nobody has ever claimed to have one. All known spiders are heterozygous -- they have a spider mutant gene paired with a normal gene.

A spinner has two gene pairs with mutant genes -- a spider mutant gene paired with a normal mutant gene and a pinstripe mutant gene paired with a normal gene. I would expect it is possible to breed a snake with two pinstripe genes and a spider mutant gene paired with a normal gene.

Examples of lethal codominant mutant genes: jaguar in carpet pythons, crested in canaries, sickle cell in humans.

An example of a lethal recessive mutant gene: jaundice in the lab mouse.

[rigomez4]

Thanks.