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G Grey Depigmentation

    Test that shows if your horse carries Grey, which makes a horse of any colour turn white as it gets...

    €49.20 BEZa barne

      AboutAbout

      This test shows whether your horse carries Grey, the gene that makes a horse born with any coat colour turn white with age, and whether it has one copy or two.

      Grey is found in many breeds. The test is useful for any breeder or owner of a horse that may be grey.

      Why test?Why test?

      Knowing before the coat changes. A grey foal looks like any other foal and may not show a white hair for months or years. The test gives the answer at birth, and it never changes.

      Breeding. You cannot tell by eye whether a grey horse has one copy or two, and that decides how many of its foals turn grey.

      Planning skin checks. Knowing early that a horse is grey lets you and your veterinarian plan regular checks.

      Telling grey from other white-looking horses. An old grey, a cremello and a horse with a white spotting pattern can all look white, but they breed on very differently.

      Clinical signsClinical signs

      Grey does not change the colour a foal is born with. It slowly removes the pigment from the hair as the horse gets older.

      What a grey horse looks like:

      • The foal is born bay, black, chestnut or any other colour
      • White hairs appear and spread with age
      • Some keep small coloured flecks all their life, known as flea-bitten grey
      • Horses with two copies usually go grey faster, and keep fewer flecks, than horses with one copy
      • The skin usually stays dark, though patches of pink, unpigmented skin are common

      Melanoma. Grey horses develop skin melanomas much more often than other horses. Studies report them in 50 to 80% of grey horses aged 15 or older. They show as firm black lumps, most often under the tail, around the anus and genitals, and on the lips and eyelids. Most grow slowly and stay benign, but some spread.

      A Grey result does not mean a horse has melanoma. Show any new lump to your veterinarian: only a veterinary examination can say what it is.

      TransmissionTransmission

      Grey is dominant. One copy is enough for a horse to turn grey. The gene is not on a sex chromosome, so colts and fillies are the same.

      What each mating can produce:

      • N/N x N/N gives 100% N/N: no grey foals
      • N/N x G/N gives 50% N/N, 50% G/N: one foal in two turns grey
      • N/N x G/G gives 100% G/N: every foal turns grey
      • G/N x G/N gives 25% N/N, 50% G/N, 25% G/G: three foals in four turn grey
      • G/N x G/G gives 50% G/N, 50% G/G: every foal turns grey
      • G/G x G/G gives 100% G/G: every foal turns grey

      Grey does not skip a generation, even when both parents are grey.

      PreventionPrevention

      The result helps in two ways: planning matings and watching grey horses for melanoma.

      Planning matings.

      • For no grey foals, both parents must be free of Grey
      • For a grey foal every time, use a parent with two copies
      • To avoid foals with two copies, mate a grey horse to a partner free of Grey

      Watching for melanoma. Ask your veterinarian to check the places listed under Clinical signs at routine visits. Treatment decisions belong to your veterinarian.

      Colour should not be the only thing that decides a mating.

      ResultsResults

      N/N: no Grey copy. The horse will not turn grey and cannot pass Grey on. It has none of the melanoma risk linked to Grey.

      G/N: one copy. The horse will turn grey with age and passes Grey to about half of its foals.

      G/G: two copies. The horse will turn grey and passes Grey to every foal. Two copies are linked to more severe melanoma than one.

      SampleSample

      EDTA blood (advised): 5 mL of whole blood in a K3-EDTA tube, collected by a veterinarian. Label the tube with the horse's name and send it with the submission form.

      Hair roots: 20 to 40 hairs pulled (not cut) from the mane or tail, with the roots attached. Tape them inside the marked area of the printable sample submission form. Hairs without roots cannot be analysed.

      White hair is not a problem. The DNA is in the root, not in the colour of the hair, so a horse that has turned white gives DNA as good as a dark one.

      Keep samples dry and at room temperature, and do not freeze them. Do not send hair that is wet, mouldy or soiled with bedding or faeces.

      Send your sample by regular mail or express delivery to:

      Equigerminal Lab HIESE
      Rua da Quinta do Sobreiro Nº25
      3230-343 Penela, Portugal

      TurnaroundTurnaround

      Standard processing: results within 5 to 10 working days of the sample arriving at the laboratory. Shipping is arranged and paid for by the client, and transit time is not included in the 5 to 10 working days.

      Samples that fail DNA extraction or amplification are repeated at no extra cost, which may add a few working days. We contact you if a new sample is required.

      How it worksHow it works

      🛒 Purchase the test: select and buy the test online.

      📧 Receive instructions: after payment confirmation you receive sample collection instructions by e-mail.

      ✨ Collect the sample yourself: pull 20 to 40 hair roots with the bulb attached, or ask your veterinarian to collect blood in a K3-EDTA tube.

      📄 Complete the form: print and complete the submission form with the animal identification.

      📮 Send it to the laboratory: Equigerminal, S.A., HIESE, Rua da Quinta do Sobreiro, 25, Quinta Vale do Espinhal, 3230-343 Penela, PORTUGAL.

      📄 Receive your report: your certified report is issued as soon as the analysis is validated.

      FAQsFAQs

      Does this test tell me my horse's original colour?
      No. Grey only removes colour. The colour underneath comes from other genes, read by the Extension and Agouti tests. If melanoma is your main concern, the Melanoma test reads Grey and Agouti together.

      Can it tell slow greying from fast greying?
      No. Two forms of Grey have been described, one that greys fast and one that greys slowly. This test shows whether Grey is present and in one or two copies, not which form the horse has.

      For ProfessionalsFor Professionals

      Genetic and clinical detail for veterinarians, geneticists and laboratories.

      • Gene / locus: STX17 (syntaxin 17), Grey (G) locus, ECA25.
      • Variant: cis-acting intronic copy-number variant of a 4.6 kb segment, increasing expression of STX17 and the neighbouring NR4A3 in pigment cells. HGVS (EquCab3.0): two copies (G2), NC_009168.3:g.6625295_6629872dup; three copies (G3), NC_009168.3:g.6625295_6629872[3].
      • Alternative designations: described as a 4.6 kb duplication by Rosengren Pielberg et al. (2008); Rubin et al. (2024) showed that the segment occurs in two (G2) or three (G3) tandem copies, with different phenotypes. OMIA lists G2 and G3 as separate variants.
      • Variant identifiers: no rs/EVA identifier listed in OMIA; OMIA variants 438 (G2) and 1732 (G3).
      • Variant classification: not currently evaluated (ISAG/AVCG, per OMIA), both G2 and G3.
      • Inheritance: autosomal dominant (OMIA code D).
      • Penetrance / expressivity: present in all 727 grey and none of 131 non-grey horses (Rosengren Pielberg et al., 2008). G3: rapid greying, usually fully white by about 10 years, high melanoma risk. G2: greying from 5 to 7 years, never fully white; no melanoma in 25 G2 Connemara ponies aged 15 to 35 (Rubin et al., 2024). Zygosity: Lipizzaners with G/G had more severe melanomas (Rosengren Pielberg et al., 2008); melanoma in 27% of G/G versus 16% of G/N Quarter Horses (Teixeira et al., 2013).
      • Melanoma prevalence: source for the figure under Clinical signs: Rubin et al. (2024). The often-quoted 70 to 80% of greys over 15 comes from earlier studies of Australian greys and Camargue mares, cited by Rosengren Pielberg et al. (2008). In 335 grey Quarter Horses: 16% at all ages, 52% over 15 years (Teixeira et al., 2013).
      • Breeds with documented carriers or cases: the same variant, from one ancient ancestor, in grey Lipizzaner, Arabian, Connemara, Thoroughbred, Welsh pony, Icelandic horse, New Forest pony and Shetland pony (Rosengren Pielberg et al., 2008); grey Quarter Horses (Teixeira et al., 2013). Particularly common in the Lipizzaner and the Arabian. Among about 1,400 horses from 78 breeds, G3 was found in 62 populations and G2 in 8 (Rubin et al., 2024).
      • Clinical / diagnostic notes for veterinarians: monitor predilection sites clinically and confirm masses histologically. ASIP genotype has been evaluated as a modifier of melanoma risk in grey Quarter Horses (Teixeira et al., 2013).

      Key references:

      • Rosengren Pielberg G, Golovko A, Sundstrom E, et al. (2008). A cis-acting regulatory mutation causes premature hair graying and susceptibility to melanoma in the horse. Nat Genet 40:1004-1009. doi:10.1038/ng.185. PMID 18641652.
      • Teixeira RBC, Rendahl AK, Anderson SM, et al. (2013). Coat color genotypes and risk and severity of melanoma in gray Quarter Horses. J Vet Intern Med 27:1201-1208. doi:10.1111/jvim.12133.
      • Rubin CJ, Hodge M, Naboulsi R, et al. (2024). An intronic copy number variation in Syntaxin 17 determines speed of greying and melanoma incidence in Grey horses. Nat Commun 15:7510. doi:10.1038/s41467-024-51898-2. PMID 39209879.

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