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G Grey Melanoma Risk Panel

Name: G Grey Melanoma Risk Panel
Brand: Equigerminal
Price: 563.0 DKK

Panel of 2 tests that shows if a grey horse has the genes linked to more skin lumps (melanomas). Reads...

563,00 kr Incl. VAT

About

This test reads the two genes linked to skin melanoma in grey horses: Grey, which makes a horse turn white with age, and Agouti, a colour gene. Grey horses get melanomas far more often than other horses.

It is for grey horses, or horses that may be grey, of any breed.

Why test?

Knowing which grey horses to watch most closely. The ranking helps you and your veterinarian plan skin checks.

Knowing early. A grey foal can be tested at birth, long before it greys or any lump appears.

Breeding decisions. Knowing both genes lets you avoid producing the combinations linked to more severe melanoma.

Two answers in one. The same report gives the Grey and Agouti genotypes, which are also useful for colour breeding.

Clinical signs

Melanomas in grey horses show as firm black lumps in the skin. They are most often found under the tail, around the anus and genitals, and on the lips and eyelids.

Studies report them in 50 to 80% of grey horses aged 15 or older
Most grow slowly and stay benign, but some spread

Transmission

The two genes are inherited separately. Each foal gets one copy of each gene from each parent, by chance. Neither gene is on a sex chromosome, so colts and fillies are the same.

Grey is dominant. One copy makes a horse grey. A G/N parent passes Grey to about half of its foals, a G/G parent to all of them. Two G/N parents give a G/G foal about one time in four.

The a version of Agouti, which gives a black base coat, is recessive. A foal is a/a only if both parents pass a. Two A/a parents give an a/a foal about one time in four. An A/A parent never produces an a/a foal.

Prevention

There are two parts: breeding choices, and watching grey horses closely.

Breeding choices.

To avoid foals with two Grey copies, mate a grey horse to a non-grey partner
To avoid foals with two copies of the a version, use at least one parent that carries no a
To avoid grey-linked melanoma altogether, use two non-grey parents: no foal will be grey

Watching grey horses. Ask your veterinarian to check the skin at routine visits, and report any new lump. Treatment decisions belong to your veterinarian.

Results

The certificate gives the Grey genotype (N/N, G/N or G/G) and the Agouti genotype (A/A, A/a or a/a). For a grey horse, it adds one of four risk categories, ranked from lower to higher:

G/N with A/A or A/a: moderate
G/N with a/a: moderate to high
G/G with A/A or A/a: high
G/G with a/a: very high

N/N at Grey: not grey. No risk category is given. The Agouti result is reported as colour information.

The categories rank grey horses against each other. They are not percentages. The Agouti part counts for less than the Grey part.

Sample

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 fine, provided the roots are attached.

Blood: 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.

Do not send tissue from a lump. 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.

Turnaround

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 works

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

📧 Receive the instructions: after payment is confirmed, you receive the sample collection instructions by e-mail.

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

✨ Collect the sample: pull 20 to 40 hair roots with the bulb and stick them in the marked area of the form, or ask your veterinarian to collect blood in a K3-EDTA tube.

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

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

FAQs

Does a very high result mean my horse will get melanoma?
No. Many grey horses get melanomas whatever their category, and some never do.

Does a moderate result mean my horse is safe?
No. Moderate is the lowest category among grey horses, not a low risk.

My horse already has a lump. Will this test tell me what it is?
No. This is a DNA test of the horse, not of the lump. Only your veterinarian can examine a lump and decide on tests or treatment.

What does the test not read?
It does not tell apart the slow-greying and fast-greying forms of Grey described in 2024, and it does not read Extension, the other base colour gene.

For Professionals

Genetic and clinical detail for veterinarians, geneticists and laboratories.

Gene / locus: two loci. STX17 (syntaxin 17), Grey, ECA25; ASIP (agouti signalling protein), Agouti, ECA22.
Variant: Grey: 4.6 kb intronic copy-number variant, NC_009168.3:g.6625295_6629872dup (G2) or g.6625295_6629872[3] (G3). Agouti a: NC_009165.3:g.26067463_26067473del; NM_001164017.1:c.187_197del.
Alternative designations: Grey was published as a 4.6 kb duplication (Rosengren Pielberg et al., 2008) and later resolved into G2 and G3 copy-number alleles (Rubin et al., 2024). Agouti a was published as c.191_201del (Rieder et al., 2001).
Variant identifiers: Grey: OMIA variants 438 (G2) and 1732 (G3), no rs/EVA identifier. Agouti a: rs3091770233; OMIA variant 509.
Variant classification: not currently evaluated (ISAG/AVCG, per OMIA) for all three variants.
Inheritance: Grey autosomal dominant (OMIA code D); Agouti a autosomal recessive for black.
Penetrance / expressivity: in 694 grey Lipizzaners, G/G horses had more severe melanoma than G/N; among horses older than 6 years, melanoma was more severe in a/a than A/A, with A/a intermediate; ASIP did not affect greying (Rosengren Pielberg et al., 2008). In 335 grey Quarter Horses, melanoma was about twice as common in G/G as in G/N, with no ASIP effect detected; prevalence 16% at all ages, 52% over 15 years and 10% under 15 years (Teixeira et al., 2013). G3 carries the high melanoma risk; none of 25 G2 Connemara ponies aged 15 to 35 had melanoma (Rubin et al., 2024).
Breeds: Grey is reported in Lipizzaners, Arabians, Connemara ponies, Thoroughbreds, Welsh ponies, Icelandic horses, New Forest ponies, Shetland ponies and Quarter Horses, and in at least 62 breeds and populations overall. Agouti occurs in all breeds.
Clinical notes for veterinarians: the risk ranking rests mainly on the Lipizzaner cohort (Rosengren Pielberg et al., 2008).

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.
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.