OMIA:002937-51751 : Skin colour, axanthism, GCH2-related in Python regius (ball python) |
Categories: Pigmentation phene
Single-gene trait/disorder: yes
Mode of inheritance: Autosomal recessive
Disease-related: unknown
Key variant known: yes
Year key variant first reported: 2025
Cross-species summary: reduction or absence of xanthophores (yellow pigments)
Species summary:
García-Elfring et al. (2025): "Wild-type ball pythons have a black background with tan saddles and traces of yellow ... . In
non-axanthic individuals, yellow pigment overlaps tan saddles but is absent from dark regions ... , whereas axanthic pythons lack yellow but retain wild-type melanin patterns ... . ... axanthic individuals have black eyes with a silvery sheen ... ."
Molecular basis: García-Elfring et al. (2025) " used whole-genome pool sequencing (pool-seq) and variant annotation. [The authors] identified a premature stop codon in the gene GTP cyclohydrolase II (gch2), which is associated with the axanthic phenotype." (omia.variant:1782).
Associated gene:
| Symbol | Description | Species | Chr | Location | OMIA gene details page | Other Links |
|---|---|---|---|---|---|---|
| gch2/LOC103050242 | GTP cyclohydrolase II | Python regius | - | no genomic information (-..-) | gch2/LOC103050242 | Ensembl |
Variants
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WARNING! Inclusion of a variant in this table does not automatically mean that it should be used for DNA testing. Anyone contemplating the use of any of these variants for DNA testing should examine critically the relevant evidence (especially in breeds other than the breed in which the variant was first described). If it is decided to proceed, the location and orientation of the variant sequence should be checked very carefully.
Since October 2021, OMIA includes a semiautomated lift-over pipeline to facilitate updates of genomic positions to a recent reference genome position. These changes to genomic positions are not always reflected in the ‘acknowledgements’ or ‘verbal description’ fields in this table.
| OMIA Variant ID | Breed(s) | Variant Phenotype | Gene | Allele | Variant Type | Variant Effect | Source of Genetic Variant | Pathogenicity Classification* | Reference Sequence | Chr. | g. or m. | c. or n. | p. | Verbal Description | EVA ID | Year Published | PubMed ID(s) | Acknowledgements |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1782 | Skin colour, axanthism | gch2/LOC103050242 | substitution | nonsense (stop-gain) | Not currently evaluated | 2 | g.281146407C>T | c.520C>T | p.(R174*) | The genomic location corresponds to chromosome 2 position 281146407 of the Burmese Python assembly | 2025 | 40235167 |
* Variant pathogenicity for single gene diseases as evaluated by an expert panel of the International Society of Animal Genetics (ISAG) Animal Genetic Testing Standardization Standing Committee
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Cite this entry
Nicholas, F. W., Tammen, I., & Sydney Informatics Hub. (2025). OMIA:002937-51751: Online Mendelian Inheritance in Animals (OMIA) [dataset]. https://omia.org/. https://doi.org/10.25910/2AMR-PV70
Reference
| 2025 | García-Elfring, A., Roffey, H.L., Abergas, J.M., Hendry, A.P., Barrett, R.D.H. : |
| GTP cyclohydrolase II (gch2) and axanthism in ball pythons: A new vertebrate model for pterin-based pigmentation. Anim Genet 56:e70011, 2025. Pubmed reference: 40235167. DOI: 10.1111/age.70011. |
Edit History
- Created by Imke Tammen2 on 17 Apr 2025
- Changed by Imke Tammen2 on 17 Apr 2025