Extensão, Castanho ou Sorrel
Teste de ADN para o gene Extension que controla a produção de pigmento preto ou vermelho em todo o pelo....
€43.05 Incl. IVA
Sobre o teste
O Teste de DNA Extension (MC1R) determina a cor base genética do pelo ao identificar se um cavalo transporta o alelo dominante do pigmento preto (E) ou o alelo recessivo do pigmento vermelho (e).
Este teste é essencial para criadores que desejam prever as cores do pelo da descendência e identificar cavalos que transportam o fator vermelho recessivo, mesmo quando apresentam uma cor de pelo baseada no preto.
Para uma previsão completa da cor do pelo, recomenda-se o teste Extension juntamente com o teste Agouti e outros testes de diluição da cor do pelo.
Porquê testar?
O gene da Extensão permite aos criadores:
- Identificar portadores do alelo recessivo vermelho (castanho).
- Prever a cor base do pelo dos futuros descendentes.
- Aprimorar as decisões de criação para a seleção da cor.
- Confirmar se os cavalos de base preta são homozigóticos ou heterozigóticos para o gene da Extensão.
- Combinar os resultados com os genes Agouti e de diluição para uma previsão completa da cor do pelo.
Sinais clínicos
This gene sets coat colour. It is not linked to any illness.
Horses that can make black pigment. Carriers and non-carriers look the same. Agouti then decides where the black goes: onto the legs, mane and tail only for a bay or brown, or all over for a black.
Chestnut horses. The coat has only red pigment. The shade runs from a pale sorrel to a very dark liver chestnut, and the mane and tail may be darker, the same shade or flaxen. Sorrel, chestnut and liver chestnut are names for the same result. Agouti has no black pigment to work on, so it does not change a chestnut.
What fools the eye:
- A very dark liver chestnut against a true black, especially in winter coat
- A sun-bleached black, which can read as dark brown or dark chestnut
- A flaxen chestnut against a palomino: both have a light mane and tail on a golden body
- A dilution on top of the base colour: Cream, Pearl, Champagne, Dun or Silver
- Grey, which slowly strips the base colour away and in the end hides it completely
Transmissão
Chestnut is recessive. A horse needs one chestnut copy from the sire and one from the dam to be chestnut. The gene is not on a sex chromosome, so colts and fillies are the same.
What each mating can produce:
- E/E x E/E gives 100% E/E: no chestnut foals and no carriers
- E/E x E/e gives 50% E/E, 50% E/e: no chestnut foals
- E/E x e/e gives 100% E/e: no chestnut foals, every foal a carrier
- E/e x E/e gives 25% E/E, 50% E/e, 25% e/e: one foal in four chestnut
- E/e x e/e gives 50% E/e, 50% e/e: one foal in two chestnut
- e/e x e/e gives 100% e/e: every foal chestnut
Prevenção
The result lets you plan whether a mating can give chestnut foals.
To get chestnut foals. Both parents must carry the chestnut variant. The crosses under Transmission give the odds.
To keep chestnut out. At least one parent must have no copy of the chestnut variant.
Breeding for black. Test both parents at Agouti too. Both must be able to pass on black.
Chestnuts and Silver. Silver only lightens black pigment, so a chestnut can carry Silver without showing it and pass it on unseen. In breeds where Silver occurs, keep this in mind: Silver is linked to an eye condition, Multiple Congenital Ocular Anomalies.
Colour should not be the only thing that decides a mating.
Descrição dos resultados
O teste de DNA para o gene Extension verifica a cor base do pelo e apresenta os resultados como um dos seguintes:
- E/E- Homozigótico Dominante para Extension - Preto, Castanho ou Marrom - Apenas o fator preto é expresso. O cavalo só pode transmitir o alelo (E) E/E à sua descendência. Não pode ter poldros com cor base Castanha ou Sorrel, independentemente da cor do parceiro. O gene Agouti determinará se a cor base do pelo será preta, castanha ou marrom, a menos que seja modificada por outros genes modificadores de cor.
- E/e - Heterozigótico para Extension - Preto, Castanho ou Marrom - Tanto o fator vermelho como o preto são expressos. Pode transmitir o alelo (E) ou (e) à sua descendência. O gene Agouti determinará se a cor base do pelo será preta, castanha ou marrom, a menos que seja modificada por outros genes modificadores de cor.
- e/e - Homozigótico recessivo para Extension - Castanho ou Sorrel- Apenas o pigmento vermelho é expresso. A cor base do pelo é castanha ou sorrel, a menos que seja modificada por outros genes modificadores de cor.
Requisitos da amostra
30 a 40 - raízes de crinas - envelope ou 5 mL - sangue - tubo K3 EDTA
Envie a sua amostra por correio normal ou entrega expressa para:
Equigerminal Lab HIESE
Rua da Quinta do Sobreiro Nº25
3230-343 Penela, Portugal
Tempo de resposta
2 a 5 dias úteis
Como funciona
🛒 Compre o Teste: Selecione e compre o teste online.
📧 Receba Instruções: Após a confirmação do pagamento, receba instruções para a recolha da amostra.
✨ Recolha da Amostra: Recolha 30–40 raízes de crinas ou peça ao seu veterinário para recolher uma amostra de sangue.
📄 Descarregue o Formulário de Submissão: Descarregue o formulário de submissão para impressão.
📮 Envie as Amostras: Envie as suas amostras para:
Equigerminal Lab HIESE
Rua da Quinta do Sobreiro Nº25
3230-343 Penela, Portugal
📄 Receba os Resultados: O seu certificado de DNA será enviado por email.
FAQs
What does this test not detect?
It does not read a second, much rarer chestnut variant called e-a. It does not test Agouti. It does not test Cream, Pearl, Champagne, Silver, Dun, Grey, Roan, Tobiano, Overo, Splashed White, Sabino, Dominant White or the Appaloosa patterns. It says nothing about health, performance or temperament.
My horse is chestnut. Do I still need the test?
Usually not, since a chestnut horse already has two chestnut copies. It still makes sense when the colour is hard to read.
At what age can a horse be tested?
Any age. The result never changes, so a newborn foal gives the same answer as an adult.
For Professionals
Genetic and clinical detail for veterinarians, geneticists and laboratories.
- Gene / locus: MC1R (melanocortin 1 receptor), Extension (E) locus, ECA3.
- Variant: e allele, c.248C>T, missense, loss of receptor function: the receptor no longer takes the hormone signal that switches the pigment cell to black pigment. HGVS (EquCab3.0): NC_009146.3:g.36979560C>T; NM_001114534.1:c.248C>T; NP_001108006.1:p.(Ser83Phe). Marklund et al. (1996) showed that chestnut in 12 breeds comes from this change.
- Alternative designations: chestnut, red factor. A second chestnut allele, e^a (NM_001114534.1:c.250G>A; NP_001108006.1:p.(Asp84Asn); NC_009146.3:g.36979562G>A; rs3443929753), was described in the Belgian Draft (Wagner and Reissmann, 2000) and is also reported in the Black Forest horse. Avila et al. (2022) concluded that detecting e^a matters when breeding to a colour.
- Variant identifiers: e: rs68458866 (EVA); OMIA variant 154. e^a: OMIA variant 155.
- Variant classification: not currently evaluated (ISAG/AVCG, per OMIA).
- Inheritance: autosomal recessive for the chestnut phenotype (e/e); E is dominant. OMIA code: A (autosomal). Recessive inheritance was first argued by Hurst (1906), disputed by Weldon the same year, and settled from studbook records in Hurst's favour.
- Breeds with documented carriers or cases: widespread. Avila et al. (2022) found e in all 28 breeds studied: Andalusian, Appaloosa, Arabian, Connemara Pony, Dutch Warmblood, Gypsy Cob, Gypsy Vanner, Hanoverian, Icelandic Horse, Knabstrupper, Lusitano, Miniature Horse, Missouri Fox Trotter, Morgan Horse, Mustang, Norwegian Fjord Horse, Oldenburg, Paint Horse, Percheron, Pony of the Americas, Pura Raza Espanola, Quarter Horse, Rocky Mountain Horse, Shetland Pony, Standardbred, Tennessee Walking Horse, Thoroughbred and Welsh Pony. e^a carriers: Knabstrupper 6/91, Paint Horse 1/2,076, Percheron 1/52, Quarter Horse 2/110 (Avila et al., 2022).
- Allele / carrier frequencies: allele frequency of e from 76% (Pony of the Americas) to 12% (Percheron) across 28 breeds (Avila et al., 2022; 11,281 horses tested, 6,878 after removal of close relatives). The authors note ascertainment bias, since samples were submitted for colour testing, so figures for less-sampled breeds may be overestimated.
- Clinical / diagnostic notes for veterinarians: the report gives the c.248C>T genotype only. An E/E or E/e horse from Belgian Draft, Knabstrupper, Paint, Percheron or Quarter Horse lines may still carry e^a; an e/e-like phenotype with an E/e result should prompt e^a testing. Source for the Silver note under Prevention: Brunberg et al. (2006). Mura et al. (2024) documented mismatch between genetic and recorded visual colour in the Sarcidano horse. Reported links between MC1R and behaviour (Jacobs et al., 2016; Finn et al., 2016) are early exploratory work and no basis for decisions.
Key references:
- Marklund L, Moller MJ, Sandberg K, Andersson L (1996). A missense mutation in the gene for melanocyte-stimulating hormone receptor (MC1R) is associated with the chestnut coat color in horses. Mamm Genome 7:895-899. PMID 8995760.
- Wagner HJ, Reissmann M (2000). New polymorphism detected in the horse MC1R gene. Anim Genet 31:289-290. doi:10.1046/j.1365-2052.2000.00655.x. PMID 11086549.
- Rieder S, Taourit S, Mariat D, Langlois B, Guerin G (2001). Mutations in the agouti (ASIP), the extension (MC1R), and the brown (TYRP1) loci and their association to coat color phenotypes in horses. Mamm Genome 12:450-455. doi:10.1007/s003350020017. PMID 11353392.
- Avila F, Hughes SS, Magdesian KG, Penedo MCT, Bellone RR (2022). Breed distribution and allele frequencies of base coat color, dilution, and white patterning variants across 28 horse breeds. Genes 13:1641.