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McFadden A, Vierra M, Robilliard H, Martin K, Brooks SA, Everts RE, Lafayette C. Population Analysis Identifies 15 Multi-Variant Dominant White Haplotypes in Horses. Animals (Basel) 2024; 14:517. [PMID: 38338160 PMCID: PMC10854588 DOI: 10.3390/ani14030517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 01/26/2024] [Accepted: 02/04/2024] [Indexed: 02/12/2024] Open
Abstract
The influence of a horse's appearance on health, sentimental and monetary value has driven the desire to understand the etiology of coat color. White markings on the coat define inclusion for multiple horse breeds, but they may disqualify a horse from registration in other breeds. In domesticated horses (Equus caballus), 35 KIT alleles are associated with or cause depigmentation and white spotting. It is a common misconception among the general public that a horse can possess only two KIT variants. To correct this misconception, we used BEAGLE 5.4-phased NGS data to identify 15 haplotypes possessing two or more KIT variants previously associated with depigmentation phenotypes. We sourced photos for 161 horses comprising 12 compound genotypes with three or more KIT variants and employed a standardized method to grade depigmentation, yielding average white scores for each unique compound genotype. We found that 7 of the 12 multi-variant haplotypes resulted in significantly more depigmentation relative to the single-variant haplotypes (ANOVA). It is clear horses can possess more than two KIT variants, and future work aims to document phenotypic variations for each compound genotype.
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Affiliation(s)
- Aiden McFadden
- Etalon Inc., Menlo Park, CA 94025, USA; (M.V.); (H.R.); (K.M.); (R.E.E.)
| | - Micaela Vierra
- Etalon Inc., Menlo Park, CA 94025, USA; (M.V.); (H.R.); (K.M.); (R.E.E.)
| | - Holly Robilliard
- Etalon Inc., Menlo Park, CA 94025, USA; (M.V.); (H.R.); (K.M.); (R.E.E.)
| | - Katie Martin
- Etalon Inc., Menlo Park, CA 94025, USA; (M.V.); (H.R.); (K.M.); (R.E.E.)
| | - Samantha A. Brooks
- Department of Animal Sciences, UF Genetics Institute, University of Florida, Gainesville, FL 32611, USA;
| | - Robin E. Everts
- Etalon Inc., Menlo Park, CA 94025, USA; (M.V.); (H.R.); (K.M.); (R.E.E.)
| | - Christa Lafayette
- Etalon Inc., Menlo Park, CA 94025, USA; (M.V.); (H.R.); (K.M.); (R.E.E.)
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2
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McFadden A, Vierra M, Martin K, Brooks SA, Everts RE, Lafayette C. Spotting the Pattern: A Review on White Coat Color in the Domestic Horse. Animals (Basel) 2024; 14:451. [PMID: 38338094 PMCID: PMC10854722 DOI: 10.3390/ani14030451] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 01/25/2024] [Accepted: 01/27/2024] [Indexed: 02/12/2024] Open
Abstract
Traits such as shape, size, and color often influence the economic and sentimental value of a horse. Around the world, horses are bred and prized for the colors and markings that make their unique coat patterns stand out from the crowd. The underlying genetic mechanisms determining the color of a horse's coat can vary greatly in their complexity. For example, only two genetic markers are used to determine a horse's base coat color, whereas over 50 genetic variations have been discovered to cause white patterning in horses. Some of these white-causing mutations are benign and beautiful, while others have a notable impact on horse health. Negative effects range from slightly more innocuous defects, like deafness, to more pernicious defects, such as the lethal developmental defect incurred when a horse inherits two copies of the Lethal White Overo allele. In this review, we explore, in detail, the etiology of white spotting and its overall effect on the domestic horse to Spot the Pattern of these beautiful (and sometimes dangerous) white mutations.
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Affiliation(s)
- Aiden McFadden
- Etalon Inc., Menlo Park, CA 94025, USA; (M.V.); (K.M.); (R.E.E.); (C.L.)
| | - Micaela Vierra
- Etalon Inc., Menlo Park, CA 94025, USA; (M.V.); (K.M.); (R.E.E.); (C.L.)
| | - Katie Martin
- Etalon Inc., Menlo Park, CA 94025, USA; (M.V.); (K.M.); (R.E.E.); (C.L.)
| | - Samantha A. Brooks
- Department of Animal Sciences, UF Genetics Institute, University of Florida, Gainesville, FL 32611, USA;
| | - Robin E. Everts
- Etalon Inc., Menlo Park, CA 94025, USA; (M.V.); (K.M.); (R.E.E.); (C.L.)
| | - Christa Lafayette
- Etalon Inc., Menlo Park, CA 94025, USA; (M.V.); (K.M.); (R.E.E.); (C.L.)
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3
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Elkin J, Martin A, Courtier-Orgogozo V, Santos ME. Analysis of the genetic loci of pigment pattern evolution in vertebrates. Biol Rev Camb Philos Soc 2023; 98:1250-1277. [PMID: 37017088 DOI: 10.1111/brv.12952] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 03/08/2023] [Accepted: 03/14/2023] [Indexed: 04/06/2023]
Abstract
Vertebrate pigmentation patterns are amongst the best characterised model systems for studying the genetic basis of adaptive evolution. The wealth of available data on the genetic basis for pigmentation evolution allows for analysis of trends and quantitative testing of evolutionary hypotheses. We employed Gephebase, a database of genetic variants associated with natural and domesticated trait variation, to examine trends in how cis-regulatory and coding mutations contribute to vertebrate pigmentation phenotypes, as well as factors that favour one mutation type over the other. We found that studies with lower ascertainment bias identified higher proportions of cis-regulatory mutations, and that cis-regulatory mutations were more common amongst animals harbouring a higher number of pigment cell classes. We classified pigmentation traits firstly according to their physiological basis and secondly according to whether they affect colour or pattern, and identified that carotenoid-based pigmentation and variation in pattern boundaries are preferentially associated with cis-regulatory change. We also classified genes according to their developmental, cellular, and molecular functions. We found a greater proportion of cis-regulatory mutations in genes implicated in upstream developmental processes compared to those involved in downstream cellular functions, and that ligands were associated with a higher proportion of cis-regulatory mutations than their respective receptors. Based on these trends, we discuss future directions for research in vertebrate pigmentation evolution.
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Affiliation(s)
- Joel Elkin
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
| | - Arnaud Martin
- Department of Biological Sciences, The George Washington University, 800 22nd St. NW, Suite 6000, Washington, DC, 20052, USA
| | | | - M Emília Santos
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
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4
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Esdaile E, Till B, Kallenberg A, Fremeux M, Bickel L, Bellone RR. A de novo missense mutation in KIT is responsible for dominant white spotting phenotype in a Standardbred horse. Anim Genet 2022; 53:534-537. [PMID: 35641888 DOI: 10.1111/age.13222] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 05/04/2022] [Indexed: 12/31/2022]
Affiliation(s)
- Elizabeth Esdaile
- Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Brad Till
- Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Angelica Kallenberg
- Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Michelle Fremeux
- InfogeneNZ, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
| | - Leslie Bickel
- Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Rebecca R Bellone
- Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, California, USA.,Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
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5
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Identification of W13 in the American Miniature Horse and Shetland Pony Populations. Genes (Basel) 2021; 12:genes12121985. [PMID: 34946933 PMCID: PMC8702037 DOI: 10.3390/genes12121985] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 12/07/2021] [Accepted: 12/11/2021] [Indexed: 11/16/2022] Open
Abstract
Coat color is a trait of economic significance in horses. Variants in seven genes have been documented to cause white patterning in horses. Of the 34 variants that have been identified in KIT proto-oncogene, receptor tyrosine kinase (KIT), 27 have only been reported in a single individual or family and thus not all are routinely offered for genetic testing. Therefore, to enable proper use of marker-assisted selection, determining breed specificity for these alleles is warranted. Screening 19 unregistered all-white Shetland ponies for 16 white patterning markers identified 14 individuals whose phenotype could not be explained by testing results. In evaluating other known dominant white variants, 14 horses were heterozygous for W13. W13 was previously only reported in two quarter horses and a family of Australian miniature horses. Genotyping known white spotting variants in 30 owner-reported white animals (25 Miniature Horses and five Shetland ponies) identified two additional W13/N American Miniature Horses. The estimated allele frequency of W13 in the American Miniature Horse was 0.0063 (79 N/N, 1 W13/N) and the allele was not detected in a random sample (n = 59) of Shetland ponies. No homozygous W13 individuals were identified and W13/N ponies had a similar all-white coat with pink skin phenotype, regardless of the other white spotting variants present, demonstrating that W13 results in a Mendelian inherited dominant white phenotype and homozygosity is likely lethal. These findings document the presence of W13 in the American Miniature Horse and Shetland pony populations at a low frequency and illustrate the importance of testing for this variant in additional breeds.
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Abstract
Genetic testing in horses began in the 1960s, when parentage testing using blood group markers became the standard. In the 1990s, parentage testing shifted from evaluating blood groups to DNA testing. The development of genetics and genomics in both human and veterinarian medicine, along with continued technological advances in the last 2 decades, has helped unravel the causal variants for many horse traits. Genetic testing is also now possible for a variety of phenotypic and disease traits and is used to assist in breeding and clinical management decisions. This article describes the genetic tests that are currently available for horses.
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Affiliation(s)
- Rebecca R Bellone
- Department of Population Health and Reproduction Davis, CA 95616, USA; Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA.
| | - Felipe Avila
- Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA
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Huang T, Pu Y, Song C, Sheng Z, Hu X. A quantitative trait locus on chromosome 2 was identified that accounts for a substantial proportion of phenotypic variance of the yellow plumage color in chicken. Poult Sci 2020; 99:2902-2910. [PMID: 32475423 PMCID: PMC7597730 DOI: 10.1016/j.psj.2020.01.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 12/02/2019] [Accepted: 01/01/2020] [Indexed: 12/12/2022] Open
Abstract
Chicken plumage color is an important economical trait in poultry breeding, as triple-yellow indigenous broilers are preferred over western commercial broilers in the Chinese market. However, the studies on the pigmentation of plumage coloration are relatively rare at present. Here, we performed a genome-wide mapping study on an F2 intercross, whose 2 founders were one hybrid commercial line “High Quality chicken Line A” that originated from the Anak red chicken and one indigenous line “Huiyang Beard” chicken that is a classical “triple-yellow” Chinese indigenous breed. Moreover, we used an automatic colorimeter that can quantitatively assess the colorations in L∗, a∗, and b∗ values. One major quantitative trait locus (QTL) on chromosome 2 was thus identified by both genome-wide association and linkage analyses, which could explain 10 to 20% of the total phenotypic variance of the b∗ measurements of the back plumage color. Using linkage analysis, 2 additional QTL on chromosome 1 and 20 were also found to be significantly associated with the plumage coloration in this cross. With additional samples from Anak red and Huiyang Beard chickens as well as pooled resequencing data from the 2 founders of this cross, we then further narrowed down the QTL regions and identified several candidate genes, such as CABLES1, CHST11, BCL2L1, and CHD22. As the effects of QTL found in this study were substantial, quantitatively measuring the coloration rather than the descriptive measurements provides stronger statistical power for the analyses. In addition, this major QTL on chromosome 2 that was associated with feather pigmentation at the genome-wide level will facilitate the future chicken breeding for yellow plumage color. In conclusions, we mapped 3 associated QTL on chromosome 1, 2, and 20. The candidate genes identified in this study shed light in the genetic basis of yellow plumage color in chicken.
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Affiliation(s)
- Tao Huang
- Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Science, Wuhan, Hubei Province, China; Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction, Ministry of Education, Huazhong Agricultural University, Wuhan, Hubei Province, China
| | - Yuejin Pu
- Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Science, Wuhan, Hubei Province, China
| | - Chi Song
- State Key Laboratory for Agro-Biotechnology, China Agricultural University, Beijing, China
| | - Zheya Sheng
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction, Ministry of Education, Huazhong Agricultural University, Wuhan, Hubei Province, China.
| | - Xiaoxiang Hu
- State Key Laboratory for Agro-Biotechnology, China Agricultural University, Beijing, China.
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Grilz-Seger G, Reiter S, Neuditschko M, Wallner B, Rieder S, Leeb T, Jagannathan V, Mesarič M, Cotman M, Pausch H, Lindgren G, Velie B, Horna M, Brem G, Druml T. A Genome-Wide Association Analysis in Noriker Horses Identifies a SNP Associated With Roan Coat Color. J Equine Vet Sci 2020; 88:102950. [PMID: 32303326 DOI: 10.1016/j.jevs.2020.102950] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 01/28/2020] [Accepted: 01/28/2020] [Indexed: 01/20/2023]
Abstract
The roan coat color in horses is characterized by dispersed white hair and dark points. This phenotype segregates in a broad range of horse breeds, while the underlying genetic background is still unknown. Previous studies mapped the roan locus to the KIT gene on equine chromosome 3 (ECA3). However, this association could not be validated across different horse breeds. Performing a genome-wide association analysis (GWAS) in Noriker horses, we identified a single nucleotide polymorphism (SNP) (ECA3:g.79,543.439 A > G) in the intron 17 of the KIT gene. The G -allele of the top associated SNP was present in other roan horses, namely Quarter Horse, Murgese, Slovenian, and Belgian draught horse, while it was absent in a panel of 15 breeds, including 657 non-roan horses. In further 379 gray Lipizzan horses, eight animals exhibited a heterozygous genotype (A/G). Comparative whole-genome sequence analysis of the KIT region revealed two deletions in the downstream region (ECA3:79,533,217_79,533,224delTCGTCTTC; ECA3:79,533,282_79,533,285delTTCT) and a 3 bp deletion combined with 17 bp insertion in intron 20 of KIT (ECA3:79,588,128_79,588,130delinsTTATCTCTATAGTAGTT). Within the Noriker sample, these loci were in complete linkage disequilibrium (LD) with the identified top SNP. Based upon pedigree information and historical records, we were able to trace back the genetic origin of roan coat color to a baroque gene pool. Furthermore, our data suggest allelic heterogeneity and the existence of additional roan alleles in ponies and breeds related to the English Thoroughbred. In order to study the roan phenotype segregating in those breeds, further association and verification studies are required.
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Affiliation(s)
- Gertrud Grilz-Seger
- Department of Animal Breeding and Genetics, University of Veterinary Sciences Vienna, Vienna, Austria.
| | - Simone Reiter
- Department of Animal Breeding and Genetics, University of Veterinary Sciences Vienna, Vienna, Austria
| | | | - Barbara Wallner
- Department of Animal Breeding and Genetics, University of Veterinary Sciences Vienna, Vienna, Austria
| | | | - Tosso Leeb
- Department of Genetics, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Vidhya Jagannathan
- Department of Genetics, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Matjaz Mesarič
- Clinic for Reproduction and Large Animals, University of Ljubljana, Veterinary Faculty, Ljubljana, Slovenia
| | - Markus Cotman
- Department for Preclinical Sciences, University of Ljubljana, Veterinary Faculty, Ljubljana, Slovenia
| | | | - Gabriella Lindgren
- Department of Animal Breeding & Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden; Livestock Genetics, Department of Biosystems, KU Leuven, Leuven, Belgium
| | - Brandon Velie
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Michaela Horna
- Department of Animal Husbandry, Slovak University of Agriculture in Nitra, Nitra, Slovakia
| | - Gottfried Brem
- Department of Animal Breeding and Genetics, University of Veterinary Sciences Vienna, Vienna, Austria
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9
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Genetic heterogeneity of white markings in Quarter Horses. Livest Sci 2020. [DOI: 10.1016/j.livsci.2020.103935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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10
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Hug P, Jude R, Henkel J, Jagannathan V, Leeb T. A novel
KIT
deletion variant in a German Riding Pony with white‐spotting coat colour phenotype. Anim Genet 2019; 50:761-763. [DOI: 10.1111/age.12840] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/01/2019] [Indexed: 11/28/2022]
Affiliation(s)
- P. Hug
- Institute of Genetics, Vetsuisse Faculty University of Bern Bern 3001 Switzerland
- DermFocus University of Bern Bern 3001 Switzerland
| | - R. Jude
- RJC Weilerswist 53919 Germany
| | - J. Henkel
- Institute of Genetics, Vetsuisse Faculty University of Bern Bern 3001 Switzerland
- DermFocus University of Bern Bern 3001 Switzerland
| | - V. Jagannathan
- Institute of Genetics, Vetsuisse Faculty University of Bern Bern 3001 Switzerland
- DermFocus University of Bern Bern 3001 Switzerland
| | - T. Leeb
- Institute of Genetics, Vetsuisse Faculty University of Bern Bern 3001 Switzerland
- DermFocus University of Bern Bern 3001 Switzerland
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Henkel J, Lafayette C, Brooks SA, Martin K, Patterson-Rosa L, Cook D, Jagannathan V, Leeb T. Whole-genome sequencing reveals a large deletion in the MITF gene in horses with white spotted coat colour and increased risk of deafness. Anim Genet 2019; 50:172-174. [PMID: 30644113 DOI: 10.1111/age.12762] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/12/2018] [Indexed: 01/18/2023]
Abstract
White spotting phenotypes in horses are highly valued in some breeds. They are quite variable and may range from the common white markings up to completely white horses. EDNRB, KIT, MITF, PAX3 and TRPM1 represent known candidate genes for white spotting phenotypes in horses. For the present study, we investigated an American Paint Horse family segregating a phenotype involving white spotting and blue eyes. Six of eight horses with the white-spotting phenotype were deaf. We obtained whole-genome sequence data from an affected horse and specifically searched for structural variants in the known candidate genes. This analysis revealed a heterozygous ~63-kb deletion spanning exons 6-9 of the MITF gene (chr16:21 503 211-21 566 617). We confirmed the breakpoints of the deletion by PCR and Sanger sequencing. PCR-based genotyping revealed that all eight available affected horses from the family carried the deletion. The finding of an MITF variant fits well with the syndromic phenotype involving both depigmentation and an increased risk for deafness and corresponds to human Waardenburg syndrome type 2A. Our findings will enable more precise genetic testing for depigmentation phenotypes in horses.
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Affiliation(s)
- J Henkel
- Institute of Genetics, Vetsuisse Faculty, University of Bern, 3001, Bern, Switzerland.,DermFocus, University of Bern, 3001, Bern, Switzerland
| | | | - S A Brooks
- Department of Animal Sciences, University of Florida, Gainesville, FL, 32611-0910, USA
| | - K Martin
- Etalon Inc., Menlo Park, CA, 94025, USA
| | - L Patterson-Rosa
- Department of Animal Sciences, University of Florida, Gainesville, FL, 32611-0910, USA
| | - D Cook
- Etalon Inc., Menlo Park, CA, 94025, USA
| | - V Jagannathan
- Institute of Genetics, Vetsuisse Faculty, University of Bern, 3001, Bern, Switzerland.,DermFocus, University of Bern, 3001, Bern, Switzerland
| | - T Leeb
- Institute of Genetics, Vetsuisse Faculty, University of Bern, 3001, Bern, Switzerland.,DermFocus, University of Bern, 3001, Bern, Switzerland
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Divergent Evolutional Mode and Purifying Selection of the KIT Gene in European and Asian Domestic Pig Breeds. BIOMED RESEARCH INTERNATIONAL 2018; 2018:8932945. [PMID: 30211229 PMCID: PMC6120332 DOI: 10.1155/2018/8932945] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 06/15/2018] [Accepted: 06/20/2018] [Indexed: 11/17/2022]
Abstract
The recent geographic expansion of wild boars and the even more recent development of numerous domestic pigs have spurred exploration on pig domestic origins. The porcine KIT gene has been showed to affect pleiotropic effects, blood parameters, and coat colour phenotypes, especially the white colour phenotype formation in European commercial breeds. Here, we described the use of SNPs to identify different selection patterns on the porcine KIT gene and the phylogenetic relationships of the inferred haplotypes. The phylogenetic tree revealed four clades in European and Asian wild and domestic pigs: two major clades with European and Asian origins and one minor clade with Iberian origins as well as the other minor clade in Asia, consistent with the major introgression of domestic Asian pigs in Europe around 18th -19th century. The domestication history of pigs, which occurred in the domestication centers (Europe and Asia), has also been demonstrated by mtDNA analysis. Furthermore, both Asian and European domestic pigs evolved under purifying selection. This study indicated that domestic pigs in Europe and Asia have different lineage origins but the porcine KIT gene was undergoing a purifying selection during their evolutional histories.
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