Fig 1.
The Albino, Lavender Albino, and Ultramel color morphs have reduced brown-to-black coloration, characteristic of a loss of melanin.
Red-to-yellow coloration is unaffected in these morphs. Hypothesized causative genes represent genes in which loss-of-function variants in other vertebrates produce similar phenotypes (Table 1). (A) Wildtype. (B) Ultramel. (C) Lavender Albino. (D-F) Albino. Phenotypes within the Albino color morph are variable, with some animals having skin patches that are white and others having skin patches that are light beige. (D) Albino animal described as an AlbAlbino homozygote. (E) Albino animal described as an AlbCandy homozygote. (F) Albino animal described as an AlbToffee homozygote. Photo credits, Ryan Young of Molecular Reptile, Chiron Graves, Phil Barclay, Michael Freedman of The Florida Reptile Ranch.
Table 1.
Loss-of-function phenotypes of melanogenesis genes across vertebrates.
Table 2.
Comparison of ball python and Burmese python genomic and protein sequences for melanogenesis genes.
Fig 2.
The Albino color morph is associated with three haplotypes of TYR.
(A) TYR haplotype frequencies among Albinos and Non-Albinos. (B) Alignment of TYR protein sequences surrounding the missense variants D394G and P384L. (C) TYR genotypes and breeder designations of animals used in the association study. +, any TYR haplotype found exclusively among Non-Albinos. (D) PCR amplification of a genomic fragment containing the variable number tandem repeat (VNTR) shown in E. Non-Albinos are examples of Non-Albinos homozygous for the longer allele of the VNTR. (E) Schematic of the three TYR haplotypes found in Albinos. The TYRAlbino haplotype contains no coding variants and no splice-site variants compared to wildtype. (A, E) Hash mark, discontinuity in the Burmese python reference genome.
Fig 3.
The Lavender Albino color morph is associated with a deletion in OCA2.
(A) Schematic of the OCA2 gene. (B) PCR amplification demonstrating the deletion in Lavender Albino. (C) PCR amplification used for genotyping the deletion in the animals in panel D. (D) Genotypes of 14 Lavender Albinos, 76 Non-Lavender Albinos, and one animal described as heterozygous for Lavender Albino. This set of animals includes the original Lavender Albino animal in which the OCA2 deletion was identified. (E) Schematic of the OCA2 haplotype found in Lavender Albinos. (A, E) Hash mark, discontinuity in the Burmese python reference genome.
Fig 4.
The Ultramel color morph is associated with a missense variant and a putative deletion in TYRP1.
(A) Alignment of TYRP1 protein sequence surrounding missense variant R305H. (B) Genotypes of 11 Ultramels and 78 Non-Ultramels. This set of animals includes the original Ultramel animal in which the R305H variant was identified. Ultramels heterozygous for R305H are presumed to be heterozygous for the putative deletion of coding regions 6 and 7; testing these animals for the putative deletion was not possible because the putative deletion cannot be detected when heterozygous. (C) Top, schematic of the TYRP1 gene. Bottom left, PCR amplifications demonstrating the putative deletion in the Ultramels lacking R305H. Bottom right, alignment of PCR amplicons to the TYRP1 gene. (D) Schematic of the two TYRP1 haplotypes found in Ultramels. (A, D) Hash mark, discontinuity in the Burmese python reference genome.
Fig 5.
Summary of genetic variants associated with the Albino, Lavender Albino, and Ultramel color morphs.
Photo credits, Ryan Young of Molecular Reptile, Chiron Graves, Phil Barclay, Michael Freedman of The Florida Reptile Ranch.