Leopard Gecko Genetics: Genome, Genes and Inheritance

Leopard gecko genetics is a young science. Three things are firmly established. The species has a published genome, sex is set by incubation temperature, and the Lemon Frost morph maps to the SPINT1 gene.

Everything else about how morphs are inherited comes from breeding records kept by hobbyists. Those records are useful but have not been tested in a lab.

This page separates the two. It shows what the papers say, how the common inheritance modes combine, and where the evidence stops. For the list of morphs themselves, see the leopard gecko morph guide.

The leopard gecko genome

Xiong and colleagues published a draft genome of the leopard gecko (Eublepharis macularius) in GigaScience in 2016. The animal sequenced was a male from a captive bred strain of Indian ancestry. The team produced 303 Gb of raw Illumina data, about 136 times coverage.

The assembly is 2.02 Gb long, close to the 2.23 Gb estimated from k mer counts. It is fragmented, with a scaffold N50 of 664 kb and a contig N50 of 20 kb. The authors annotated 24,755 protein coding genes, and repeats make up about 42% of the sequence.

Two quality checks differ. The assembly captured 91% of core genes in the CEGMA test but 58% in the BUSCO test. It was good enough to map a gene, as the Lemon Frost work later showed.

A revised, chromosome scale genome followed. Pinto and colleagues (Journal of Heredity, 2023) assembled about 2.24 Gb into 132 contigs. The contig N50 is 80 Mb and the scaffold N50 is 146 Mb.

The species has 19 pairs of acrocentric chromosomes, so 2n = 38.

The reference animal carried what the authors call the recessive Tremper albino allele and the incomplete dominant Lemon Frost allele. The 2016 paper also notes what sets the family Eublepharidae apart from typical geckos: no adhesive toe pads and movable eyelids.

Sex is set by incubation temperature

Leopard geckos have temperature dependent sex determination, according to the Animal Diversity Web. The sex of a hatchling depends on how warm the egg was during incubation, not on a sex chromosome pair. Eggs hatch in 45 to 53 days at 28 C.

A clutch cannot be planned for sex the way a Punnett square plans color. Genes decide color, and incubation temperature decides sex. The pattern is not a simple line, because both cool and very warm eggs produce females.

The same study found that incubation temperature shapes adult behavior. Geckos from the male biased temperature were more aggressive as adults, and females from that temperature were less attractive to males. Temperature therefore changes more than sex, and it does not touch color genes.

Lemon Frost: the one morph with a proven gene

Guo and colleagues (PLoS Genetics, 2021) studied the Lemon Frost morph. They genotyped 188 animals by RAD sequencing: 33 homozygous, 116 heterozygous and 39 wild type. They also ran pooled sequencing on separate groups of 25, 63 and 71 animals.

The trait is autosomal and semidominant, which means incompletely dominant. One copy of the allele produces the Lemon Frost look, and two copies produce a stronger one, with thicker skin and eyelids. The signal maps to SPINT1, a gene for a transmembrane serine protease inhibitor that acts as a tumor suppressor.

The exact causal change is not pinned down. The authors found two synonymous exon changes, intronic insertions and deletions, and a 13 nucleotide insertion in the 3 prime untranslated region. Extra iridophores make the pale skin, and normal geckos have none (Szydlowski and colleagues, 2020).

The health cost is real.

More than 80% of animals carrying the allele developed white iridophoromas, a skin tumor, between 6 months and 5 years of age. Homozygous animals had white ventral patches and nodules in the liver and mouth. Szydlowski and colleagues called the trait codominant, meaning the same pattern, and advised against breeding Lemon Frost until the disease is understood.

How leopard gecko genetics modes combine

Three modes cover most morph talk. A recessive trait shows only with two copies, so a carrier looks normal.

An incompletely dominant trait shows in carriers, and the two copy form (the super form) looks stronger or different. A dominant trait shows with one copy and, in principle, looks the same with two.

For the general rules and Punnett squares, use the morph genetics guide instead of a species page. The point here is narrower.

Outside Lemon Frost, no leopard gecko morph has a peer reviewed inheritance study. Pinto and colleagues (2023) do describe Tremper albino as recessive when listing their reference animal’s traits.

The Animal Diversity Web names high yellow, chocolate and albino as trade morphs, and describes the wild type as yellow with irregular black spots and a white belly. It does not describe how any of these are inherited.

Worked examples with evidence labels

The table labels each trait by its evidence. “Hobby label” means: hobby name, inheritance reported by breeders, not independently tested. Treat those rows as working assumptions, not facts.

With the one proven mode, a Lemon Frost carrier bred to a normal gecko produces, on average, half carriers and half normal hatchlings. Two carriers bred together give, on average, one homozygous, two heterozygous and one normal in four. The same arithmetic fits any incompletely dominant hobby trait, but it is only as reliable as the label.

For recessives, two visibly normal carriers give on average one in four affected hatchlings. Because carriers cannot be told apart by sight, breeders rely on records of past crosses. The leopard gecko morph calculator runs these ratios, and it uses the same hobby labels.

Health linked traits

Lemon Frost tumors are the best documented case, and Enigma syndrome is the second. A 2023 preprint by Kronke, which is not peer reviewed, describes it as a heritable disease from color morph breeding. It has a chronic form in which the animal cannot eat by itself and an acute form with seizures.

It also reports that Switzerland banned the Enigma morph in 2015 as torture breeding.

The preprint abstract does not state how Enigma is inherited or which gene is involved. Reports of eye problems in Eclipse animals and of problems in super forms are hobby reports that no veterinary or peer reviewed source has tested. Check the leopard gecko color guide for the visible traits, and see a reptile veterinarian before breeding any line with neurological or skin signs.

What is still unknown

• Albinism genes: no published gene for any leopard gecko albino line exists, so whether the three albino lines involve different genes is untested. Tremper albino is at least described as recessive in a peer reviewed genome paper.
• Enigma: the inheritance mode and gene are not stated in the preprint abstract.
• Sex determination genes: the temperatures are known, but the genes that respond to them in this species are not mapped.
• Later Lemon Frost papers (Hastings and colleagues, 2026, and Boulanger and colleagues, 2025) are cited by OMIA and are not used here.

For now, sound leopard gecko genetics means trusting the named studies and labeling everything else. The broader family of reptile color work sits in the reptile morph overview.

Frequently Asked Questions

Has the leopard gecko genome been sequenced?

Yes, as a draft. Xiong and colleagues (2016) assembled 2.02 Gb from a male and annotated 24,755 protein coding genes. Repeats make up about 42% of it.

Is there a genetic test for leopard gecko morphs?

No commercial test is on record, and the only mapped morph gene is at the SPINT1 region for Lemon Frost. Guo and colleagues did not pin down the exact causal variant. Breeders therefore rely on cross records for the other traits.

Can I choose the sex of leopard gecko babies?

Sex depends on incubation temperature, so temperature is the lever, not a gene pairing. In one study, 26 C gave all females, 32.5 C gave about 75% males, and 34 C gave about 95% females. Eggs hatch in 45 to 53 days at 28 C.

Why is Lemon Frost considered risky?

In the Guo study, more than 80% of animals carrying the allele developed iridophoromas. Homozygous animals also showed liver and mouth nodules. Szydlowski and colleagues advised against breeding the morph until the disease is understood.

Are leopard gecko albino lines the same gene?

Breeders report three separate recessive lines named Tremper, Bell and Rainwater. Tremper is described as recessive in a 2023 genome paper, but no gene has been mapped for any line. Pairing two lines and checking the offspring is the only way breeders test it.