Genetics and Morphs

The short version

• The three albino strains (Tremper, Bell, Rainwater) are separate genes and do not mix [30][31].
• Mack Snow is incomplete dominant; two copies make a Super Snow [36].
• "Giant" is the most disputed gene in the species [37].
• Avoid Enigma (a neurological syndrome) and Lemon Frost (skin tumors), plus any combo that contains them [10][34].
• There are no commercial DNA tests for leopard gecko morphs or sex [44].

Words to know

• Recessive: two copies are needed to show the trait. One copy makes a "het," which looks normal.
• Dominant: one copy shows the trait, and two copies look the same.
• Incomplete dominant: one copy shows the trait, and two copies give a stronger "super" form.
• Line-bred (polygenic): no single gene. The look is built by selection and fades without it.

The three albino strains

There are three separate albino mutations. All are simple recessive, and they are not compatible with each other: Tremper Albino x Bell Albino gives normal-looking babies that are het for both strains, not albinos [30][31].

Points to know:

• Albinos have less eye pigment, and breeders widely report light sensitivity. Published studies have not looked at it [30][31]. Give albinos a dim hide.
• Cooler incubation tends to give darker, browner Trempers; warmer gives paler, yellower geckos (breeder experience, not proven).
• Every albino should come with a strain name. "Albino" with no strain is a red flag; the gecko may already be a cross-strain het [31].

Mack Snow and Super Snow (incomplete dominant)

Mack Snow is the standard example of an incomplete dominant trait in leopard geckos [32][36]. Hatchlings are black-and-white banded with little or no yellow. Adults keep a reduced-yellow, high-contrast look.

Breeding outcomes [36]:

• Snow x Normal: 50% Snow, 50% Normal.
• Snow x Snow: 25% Normal, 50% Snow, 25% Super Snow.
• Super Snow x Normal: 100% Snow.

Super Snow is the two-copy form: a white body, dense black speckling and solid black eyes (the eye description is keeper experience). Super Snow Albinos appeared around 2006–2007 [32]. TUG Snow and Gem Snow behave the same way [36]. Whether they are the same gene as Mack Snow is debated, so the line name should stay on the label.

Health note: some hobbyists report facial deformities in Super Snows. Experienced keepers say they have not seen it and suspect incubation problems. This is debated and unproven [26]. Super Snows and Mack Snows are also reported to be harder to temp-sex [26].

Eclipse (recessive) and the RAPTOR, RADAR and TYPHOON combos

Eclipse is a simple recessive trait, first produced in 2004 and first released as part of the RAPTOR combo [27].

What it does [27]: solid eyes (fully pigmented, no visible pupil) or snake eyes (partly pigmented). Not every Eclipse shows it. Some hatch solid-eyed, some snake-eyed and some normal-eyed, and the eyes can change with age. Other markers include white or pink limbs; a white nose, feet and tail tip; white around the mouth; and black speckles on the tail. Snake eyes also turn up in Blizzard lines without the Eclipse gene, so eyes alone do not prove Eclipse [27][28].

The combos are all Eclipse plus one albino strain [27]:

An APTOR is a Tremper Albino that is 100% het for Eclipse, so it does not show the Eclipse traits [27][26]. No health issues are known beyond albino light sensitivity [26].

Blizzard and Murphy Patternless (two separate recessives)

Blizzard is a simple recessive first produced in 1995 [28]. Hatchlings are fully patternless and stay that way. Body color runs from white to yellow to purple-gray and shifts with age and incubation temperature. Darker geckos are sold as "Midnight Blizzard" and yellower ones as "Banana Blizzard." Snake or eclipse-type eyes sometimes appear without the Eclipse gene [28].

Murphy Patternless is also simple recessive and looks similar as an adult, but hatchlings are born spotted and lose the pattern as they grow (keeper experience, not proven). It is named for Pat Murphy, from the early 1990s (keeper experience, not proven).

They are different genes. Morphpedia says a true Banana Blizzard carries two copies of both [28], which only works if they are separate genes. Blizzard x Murphy Patternless gives normal-looking double hets, not patternless babies.

Named combos [28]:

• Blazing Blizzard: Tremper Albino + Blizzard.
• Diablo Blanco: Tremper Albino + Blizzard + Eclipse.

Giant and Super Giant

Morphpedia says Giant is thought to be an incomplete dominant trait, first produced by Ron Tremper in 2000, and notes an ongoing debate over whether it is incomplete dominant, recessive or line-bred [33]. Under the incomplete dominant model:

• Giant is one copy; Super Giant is two copies.
• Giant x Giant: 25% Normal, 50% Giant, 25% Super Giant [35].
• Super Giant x Super Giant: 100% Super Giant. Normal x Super Giant: 100% Giant [35].

Leopard Gecko Wiki gives these sizes: Giants generally exceed 100 g, Super Giants generally exceed 130 g, and the largest recorded Super Giant, Tremper's "Moose," weighed 156 g and measured 11 3/8 in (29 cm) [35]. Normal adults run roughly 45–90 g and 6.5–8 in (16.5–20 cm) [1]. A hobby thread quotes Giants at 85–110 g and 9–11 in (23–28 cm), figures the thread itself does not confirm [37].

The honest position: this is the most disputed "gene" in the species. Experienced keepers argue that Giant and Super Giant are bloodline names (the Moose line, the Godzilla line) rather than a proven single gene, and that the trait may not be a single gene at all. One poster reports that Tremper later concluded it was recessive [37]. Weight alone proves nothing, because a fat gecko is heavy too. Length and lineage are better tests, and a hatchling cannot be called a Giant until it is grown [35][37][38].

We recommend buying a "Giant" only with a known Giant-line pedigree, and describing juveniles as "from Giant parents," not as Giants.

Line-bred traits: Tangerine, Carrot Tail, Hypo, Super Hypo, Baldy

These are not single genes. They are built by pairing the best-looking geckos for generations. Line names (Blood, Electric, Inferno and others) matter, because the look is in the line, not in a Punnett square.

All of the following are line-bred (keeper experience; the Rainwater reference also refers to "tangerine lines" [31]):

A pairing of two SHTCT geckos gives a range of babies. Each hatchling should be described by what it shows, not by what its parents were.

White and Yellow is also listed by Morphpedia as a line-bred trait, quoting Tremper. It shows up in about 50% of first- and second-generation babies, so it looks dominant [39]. Its health debate is covered below.

Morphs to avoid

Enigma: avoid, and never breed

Enigma is a dominant morph that hatched unexpectedly in Mark Bell's collection in 2006 [10][40]. Hatchlings have blotches instead of bands and an almost all-white tail. One-copy and two-copy Enigmas look the same [10].

Enigma Syndrome is a neurological disorder tied to the Enigma gene. Signs include head bobbing, "stargazing," circling, rolling over, seizures, extreme light sensitivity, being unable to catch prey, and refusing food [10][40][17]. Severity varies between geckos and with stress. There is no cure, and severely affected geckos may need assisted feeding for life [17]. A 2013 breeder analysis of breeding records by Ben Bargen concluded that the syndrome behaves as a dominant condition linked to the Enigma gene, often starting late and getting worse over time. He called it a working hypothesis, and the question is not fully settled [41].

Status in the hobby [10]: MorphMarket does not allow Enigma sales, and the International Herpetological Society in Europe bans Enigma-carrying geckos at its events. Efforts to breed the syndrome out have repeatedly failed, and Morphpedia warns against breeders claiming "ES-free" Enigmas. Morphpedia mentions a Texas A&M study; no published result is available yet.

Because Enigma is dominant, every combo that contains it carries the same risk. That includes Dreamsicle (Enigma + Mack Snow + RAPTOR), Nova (Enigma + RAPTOR), Stealth (Enigma + Mack Snow + RADAR) and Bee (Enigma + Eclipse) [10]. One-copy and two-copy Enigmas look identical, and there is no DNA test, so we recommend avoiding any gecko with Enigma in its genes or an Enigma parent.

Lemon Frost: avoid

Lemon Frost is an incomplete dominant mutation that causes white coloring and iridophoromas, which are skin tumors of the pigment cells. Guo and colleagues (PLoS Genetics, 2021) mapped it to a region containing SPINT1, a tumor-suppressor gene also linked to human melanoma [34]. Roughly 80% of Lemon Frosts develop tumors within five years [42]. It is the one morph with a published gene-level health finding.

Noir Désir Black Eye (NDBE): avoid until there is better evidence

Hobby reports list eye deformities and possible infertility. These reports are anecdotal [26]. We recommend leaving it alone for now.

White and Yellow: buy with care

White and Yellow first appeared in a European collection in 1996 and entered the trade in 2002 [39]. Some breeders report "White and Yellow Syndrome," a mild balance or coordination problem, usually over-stepping when walking. Other collections see nothing [39]. One experienced keeper reports that some White and Yellow x White and Yellow pairings produce affected babies and others never do, with "not a lot of hard data or proof" (hobby report) [43]. Morphpedia reports that one breeder's test pairings concluded White and Yellow is not Enigma (no Enigma eye traits, no stargazing or spinning), and that the balance issue may be limited to certain lines and breedable out in one or two generations [39].

It is not on our avoid list, but we recommend:

• Avoid White and Yellow x White and Yellow and White and Yellow x Enigma pairings.
• Buy only from lines with no reported balance problems.
• Watch any White and Yellow gecko for wobbling before you bring it home.

"Debated, no proof either way" is the honest label [26][39][43].

Debated, but not on the avoid list

• Super Snow facial deformities, likely related to incubation [26].
• Albino light sensitivity, which is real but manageable [30][31][26].

DNA testing: what exists

Short answer: almost nothing.

• The main US reptile DNA-testing lab runs shed-skin morph tests for ball pythons, corn snakes and blood pythons. It offers no leopard gecko morph tests, and its DNA sex test does not work on leopard geckos, because temperature sets sex, not chromosomes [44].
• On a long-running gecko forum, keepers report that the only leopard gecko DNA tests offered are sexing and a Cryptosporidium (disease) test, with no morph tests, because the research has not been done (hobby report) [45].
• The only mapped morph gene is Lemon Frost (SPINT1) [34]. That is a research finding, not a commercial test.

What this means for you: every "het" or "possible het" claim rests on parentage and test breeding, not lab work, so buy from breeders who keep records. No test can clear a gecko from an Enigma line, which is why the advice is to avoid Enigma lines entirely. The one lab test worth running on a new gecko is a fecal test for Cryptosporidium. That is a health screen, not genetics [45].

How to read a listing

Example: "Mack Snow Tremper Albino het Eclipse, 66% het Rainwater, female, temp-sexed, 2025"

Red flags:

• "Albino" with no strain name [31].
• "Giant" on a juvenile, or with no line named [35][37].
• Enigma, Dreamsicle, Nova, Stealth, Bee or "ES-free Enigma" anywhere in the name [10].
• Lemon Frost in any combo [34][42].
• "100% het" without saying which parent was visual.
• Three or four stacked percent-hets. This is probably a normal gecko with a story.

Green flags:

• A strain name on every albino.
• Line names and parent photos for Tangerine and Hypo geckos.
• Weight in grams and a real hatch date.
• The incubation temperature stated, and sex given as "probable."