These siblings above (one obviously older than the other) both have what we call Whiteout lateral markings. The one on the right is an Extreme Whiteout, or “Whitewall” as some call it. This is a highly variable trait that, in lower expression specimens, can be difficult to spot to the untrained eye.
Whiteout is what I named the gene or trait behind the Whitewall appearance. A Whitewall is actually just an Extreme Whiteout, where solid white lateral markings span the sides from limb to limb.
I've technically been working with these since 2004 or 2005, but it did not start off as a selective breeding project. Rather, the Whitewalls seemed to just pop up out of nowhere. It wasn’t until then, when I had accidentally produced a Whitewall, that I realized we had something going on.
Eventually I realized the less extreme form of the Whitewall appearance was so subtle in some animals that I didn't think anything of it. I had sold a ton of Whiteouts over the years with no idea they were capable of producing "Whitewalls". This explains why several breeders had "Whitewalls" just popping up out of nowhere, from adults that didn't really seem to have the trait.
Above is a Tangerine x Lavender/Black Pinstripe with some very attractive Whiteout markings. Note that the Whiteout lateral markings have taken on a pinkish tone, due to the presence of Tangerine pigment.
While it might be difficult for some to believe, I can tell you with absolute certainty that Whiteout lateral markings, like you see on this page, are the less extreme form of the Whitewall trait, as we have now produced hundreds, if not thousands, of Whiteouts, and well over 100 Whitewalls.
I'm not yet 100% positive, but I am almost certain this is a co-dominant genetic mutation. Specifically, a mutated allele of the same gene responsible for lateral "porthole" markings and lateral striping, which is seen in many crested geckos.
If it is co-dominant, that means Whiteout x Whiteout should produce 1/4 Extreme Whiteout (Whitewall), 1/4 Non-Whiteout, and 1/2 Whiteout.
Below are some various examples of known Whiteout/Whitewalls
As you can see, other pattern elements, like Harlequin, Tiger and Lateral Striping, can have an impact on Whiteout/Whitewall markings, making for some great looking "combos" like we see in pattern morphs of other species.
Above is a C2/Citrus line Soft Scale with some very nice "Whitewalls".
Great example of aberrant Whiteout markings on a gorgeous Tri-Color Halloween Harlequin Pinstripe
This gecko is a good example of one that could be a really nice Whiteout, or it could be a lower expression Extreme Whiteout (Whitewall).
C2 Citrus line Soft Scale with Whiteout markings and Tangerine pigment. This is one of my favorite geckos ever.
Tangerine/Citrus line Pinstripe with Extreme Whiteout or Whitewall markings.
This is an Extreme Whiteout, or Whitewall. The pattern doesn't cut straight across, so some might argue it's not a Whitewall, but it is still, both genetically and morphologically, the same thing.