Explicit evidence for a missense mutation in exon 4 of SLC45A2 gene causing the pearl coat dilution in horses

Abstract

SummaryFour loci seem responsible for the dilution of the basic coat colours in horse: Dun (D), Silver Dapple (Z), Champagne (CH) and Cream (C). Apart from the current phenotypes ascribed to these loci, pearl has been described as yet another diluted coat colour in this species. To date, this coat colour seems to segregate only in the Iberian breeds Purebred Spanish horse and Lusitano and has also been described in breeds of Iberian origin, such as Quarter Horses and Paint Horse, where it is referred to as the ‘Barlink Factor’. This phenotype segregates in an autosomal recessive manner and resembles some of the coat colours produced by the champagne CHCH and cream CCr alleles, sometimes being difficult to distinguish among them. The interaction between compound heterozygous for the pearl Cprl and cream CCr alleles makes SLC45A2 the most plausible candidate gene for the pearl phenotype in horses. Our results provide documented evidence for the missense variation in exon 4 [SLC45A2:c.985G>A; SLC45A2:p.(Ala329Thr)] as the causative mutation for the pearl coat colour. In addition, it is most likely involved as well in the cremello, perlino and smoky cream like phenotypes associated with the compound CCr and Cprl heterozygous genotypes (known as cream pearl in the Purebred Spanish horse breed). The characterization of the pearl mutation allows breeders to identify carriers of the Cprl allele and to select this specific coat colour according to personal preferences, market demands or studbook requirements as well as to verify segregation within particular pedigrees.

Frameshift Variant in MFSD12 Explains the Mushroom Coat Color Dilution in Shetland Ponies

“…Six alleles (cream, pearl, sunshine, champagne, dun, silver) have been described in the horse that dilute either pheomelanin, eumelanin or both. Three of these alleles are caused by variants in SLC45A2 ; cream ( Cr ) c.457G>A, pearl ( Prl ) c.985G>A, sunshine ( Sun ) c.586G>A are thought to disrupt protein function and subsequent trafficking of molecules to the melanosomes resulting in a reduction of pigment production [3,4,5]. Both Prl and Sun follow a recessive mode of inheritance and dilute both eumelanin and pheomelanin, while Cr shows an incomplete dominant mode of inheritance and affects pheomelanin in a heterozygous state and both pheomelanin and eumelanin in a homozygous state [3].…”

Spotting genome-wide pigmentation variation in a brown trout admixture context

“…Elworthy, Lister, Carney, Raible, & Kelsh, 2003; Greenhill, Rocco, Vibert, Nikaido, & Kelsh, 2011; Nüsslein-Vollard & Singh, 2017), and SLC45A2 in proton-transport and osmoregulation of melanosomes resulting in colour dilution as observed in medaka (Fukamachi, Shimada, & Shima, 2001) and other organisms (e.g. tiger: Xu et al, 2013; human: Adhikari et al, 2019; horse: Sevane, Sanz, & Dunner, 2019). PEML (premelanosome protein) also contributes to eumelanin deposition and colour dilution in tetrapods (Raposo & Marks, 2007; Ishishita et al, 2018).…”

Transcriptome profiling analysis reveals key genes of different coat color in sheep skin

“…In Bos taurus (cattle) with plateaued light-colors, PMEL mutation affects melanin synthesis and plays a semi-dominant role in color determination (Schmutz & Dreger, 2013). Two mutations in the PMEL gene cause the silvery phenotype of the hourse Equus caballus (Sevane, Sanz & Dunner, 2019) and may cause the plumage of Gallus gallus to be smoky cyan gray or white (Kerje et al, 2004). Deactivation of PMEL in mice caused a large reduction in eumelanin in hair, which plays an important role in maintaining epidermal pigment deposition, but only slightly affected the hair color phenotype of mice (Hellström et al, 2011).…”

“…Missense mutations can also cause albinism in dogs (Wijesena & Schmutz, 2015). An exon four mutation of SLC45A2 gene may be related to pearl coat color (Sevane, Sanz & Dunner, 2019). In our study, the SLC45A2 gene was enriched in the cellular component, melanosome membrane; and in the two BP, melanin biosynthetic process and developmental pigmentation.…”