A TYR‐iffic discovery: Identification of a second TYR variant associated with acromelanism in dogs

• DOI: 10.1111/age.13496
• Publication Date: 2024-12-22T23:48:56Z
• Authors: Samantha L. Van B...; Anushka Panjwani; Carrie J. Finno
• Keywords: Oculocutaneous albinism; Coat; Melanosome

Acromelanism is a form of albinism that results from pigmentation being affected by temperature and causes 'Himalayan' or 'colorpoint' coat pattern in animals. Tyrosinase, encoded the TYR gene, an enzyme essential for biosynthesis melanin (Slominski, 2002). The Himalayan color, where extremities are darker torso remains lighter, due to mutations result temperature-sensitive tyrosinase protein synthesis occur only cooler areas body. Mutations associated with Himalayan-type phenotype have been identified multiple species, including cats (Lyons et al., 2005; Schmidt-Küntzel Yu 2019), rabbits (Aigner 2000), mice (Beermann 2004; Kwon 1989), mink (Benkel 2009), dogs (Bychkova 2021), baboons (Koga 2020), syrian hamsters (Sakamoto & Hirobe, 2023) domesticated canaries (Guimarães-Moreira 2024). Some as resulting complete (Imes 2006; Yan 2019). In humans, this gene impact classified Type 1 oculocutaneous (Spritz 1997). Oculocutaneous group inherited disorders characterized reduced skin, hair eyes. Six types described humans linked distinct genes (Yang 2019): (OCA1), OCA2 (OCA2), TYRP1 (OCA3), SLC45A2 (OCA4), SLC24A5 (OCA6) LRMDA (OCA7). dogs, affecting four those genes, comprising (Caduff 2017b), (Hrckova Turnova 2017; Schmutz 2002; Van Buren 2021; Wright 2019) 2017a; Winkler 2014; Wijesena Schmutz, 2015). Here, we investigated family rescue display characteristic color report second variant canids. Buccal samples were collected one non-Himalayan five written consent obtained all owners participate research. These six individuals (CP1, CP2, CP3, CP4, CP5 CP6) two litters (three each) surrendered same shelter approximately 6 months apart information they parents who do not color. entire coding sequence was sequenced CP1 then exon subsequently other individuals, using previously primer sequences 2021). Genotyping performed Sanger sequencing at UC Berkeley Sequencing Facility visualized sequencher 5.4.6 software. We novel (c.229C>T, p.Arg77Trp) homozygous state dogs. This predicted be deleterious function PredictSNP consensus classifier 87% confidence has named 'ch2' variant. All ch2/ch2 dog wild type, shown Figure 1. Interestingly, ch2 codon first (c.230G>A, p.Arg77Gln) A commercial test conducted through Davis Veterinary Genetics Laboratory evaluate background individuals. genetic presented Table S1. To assess kinship between confirm suspected relatedness, short tandem repeat panel Laboratory. matrix constructed each pair 53 autosomal repeats, proportion shared alleles assessed, similar previous reports (Sosiawan 2019; Yudianto 2022). Based on Mendelian inheritance assuming non-linkage, full siblings expected exhibit 25% two-allele sharing, 50% one-allele sharing no-allele (Moffatt 1994). analysis, potential exhibited 9.4–26.4% 64.2–90.6% 0–13.2% no allele (Table S2), suggesting some deviation 25–50–25% expectation but still indicating degree relatedness. increased observed may also indicate inbreeding effects, which can shift ratios away predictions (Kamarudin 2020). suspect de novo line, it any 668 domestic 54 canids present Dog Biomedical Variant Database Consortium (Plassais Given both presumed predict recessive, species well mutation Samantha L. Buren: Conceptualization; investigation; writing – original draft; methodology; validation; visualization; review editing; software; formal analysis; data curation. Anushka Panjwani: Validation; editing. Carrie J. Finno: Writing project administration; supervision; resources. work supported Jastro-Shields Scholarship College Agriculture Environmental Sciences, University California Davis. Thanks go Oconee Humane Society providing information, samples, photos. authors declare conflicts interest. relevant available manuscript text supporting information. S2. Please note: publisher responsible content functionality supplied authors. Any queries (other than missing content) should directed corresponding author article.