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Pearl Dilution Test

    Reads the SLC45A2 Pearl dilution, variant c.985G>A, a recessive version of the same gene that carries Cream.The report gives the...

    €43.05 Incl. VAT

      AboutAbout

      This test shows whether your horse carries Pearl, a coat colour dilution.

      It is most useful for Iberian horses, where Pearl is most common, and for anyone breeding pale colours with Cream horses.

      Why test?Why test?

      Finding hidden carriers. The DNA test is the only way to find a carrier before it is mated.

      Breeding. Knowing the result of both parents tells you whether a mating can give a Pearl dilute.

      Explaining an unexpected pale foal. Testing the parents for Pearl and Cream shows where the colour came from.

      Registration and sale. The result is objective information you can show a buyer, and a documented Pearl carrier is worth more than an untested horse.

      Clinical signsClinical signs

      Pearl lightens the coat only in some combinations.

      One copy on its own: nothing visible. The horse looks like an ordinary bay, black or chestnut.

      Two copies: red and black pigment are both lightened. On a chestnut the coat goes a pale apricot or pale gold; on a bay or a black the lightening is there but more muted. The skin is pale and the eyes are often light.

      One Pearl with one Cream: the horse looks like a cremello, a perlino or a smoky cream. In the Pura Raza Espanola this is called cream pearl. It looks like a double cream but passes its colour on very differently.

      What fools the eye:

      • A chestnut with two Pearl copies read as a pale palomino
      • Champagne, which also lightens the coat and the eye but comes from a different gene, shows with a single copy and needs its own test

      Health. No disease is linked to Pearl. Pale skin and light eyes are part of the colour, not a defect.

      TransmissionTransmission

      Pearl is recessive. A horse needs two Pearl copies, or one Pearl and one Cream, before anything shows in the coat. 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
      • N/N x N/Prl gives 50% N/N, 50% N/Prl
      • N/N x Prl/Prl gives 100% N/Prl
      • N/Prl x N/Prl gives 25% N/N, 50% N/Prl, 25% Prl/Prl
      • N/Prl x Prl/Prl gives 50% N/Prl, 50% Prl/Prl
      • Prl/Prl x Prl/Prl gives 100% Prl/Prl
      PreventionPrevention

      The result tells you which matings can give a Pearl dilute.

      To get a Pearl dilute. Both parents must carry Pearl.

      To get a cream pearl. Mate a horse carrying Pearl to a horse carrying Cream. The foal can be dilute even though neither parent is.

      To avoid an unexpected dilute. Test both parents for Pearl and Cream. If one parent tested negative for both, no foal can be dilute from this gene.

      Carrying Pearl is no reason to exclude a horse from breeding.

      ResultsResults

      N/N: negative. No Pearl copy. Cannot pass Pearl on.

      N/Prl: carrier, one copy. Passes Pearl to about half of its foals.

      Prl/Prl: two copies, a Pearl dilute. Passes Pearl to every foal.

      One limit of this test. It reads Pearl only, not Cream. A horse with one Pearl and one Cream is reported here as N/Prl. To recognise that combination, you need the Cream result as well.

      SampleSample

      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.

      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.

      One sample covers Pearl and Cream if both tests are ordered together.

      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

      What else does this test not detect?
      It does not read Sunshine or Snowdrop, two further dilutions in the same gene that can look like Pearl. It does not test Champagne, Silver, Dun, Grey, Mushroom, the base colour or any white pattern. It says nothing about health, performance or temperament.

      At what age can a horse be tested?
      Any age. The genotype is fixed at conception and never changes.

      What else decides how a Pearl dilute looks?
      Its base colour. The Extension and Agouti tests show it.

      For ProfessionalsFor Professionals

      Genetic and clinical detail for veterinarians, geneticists and laboratories.

      • Gene / locus: SLC45A2 (formerly MATP), Cream (C) locus, ECA21. Pearl and Cream are alleles of the same gene.
      • Variant: C^prl (Pearl) allele, missense in exon 4. HGVS (EquCab3.0): NC_009164.3:g.31709690G>A; XM_001498110.4:c.1129G>A; XP_001498160.2:p.(Ala377Thr).
      • Alternative designations: published as chr21:g.31,709,654G>A, exon 4 c.985G>A, p.Ala329Thr (Sevane et al., 2019). OMIA restates the variant against a more recent RefSeq transcript and HGVS rules, which shifts the c. and p. numbering (c.985 to c.1129; Ala329 to Ala377) and the listed genomic coordinate. Laboratory allele symbol: Prl.
      • Variant identifiers: rs3101690631 (EVA); OMIA variant 1069.
      • Variant classification: not currently evaluated (ISAG/AVCG, per OMIA).
      • Inheritance: autosomal recessive for dilution (Prl/Prl); a single Pearl copy dilutes in compound heterozygosity with Cream (Cr/Prl), described by Sevane et al. (2019) and Holl et al. (2019). OMIA code: A (autosomal).
      • Breeds with documented carriers or cases: documented in American Paint Horse, Lusitano, Pura Raza Espanola and Quarter Horse. Detected in seven of 28 breeds surveyed: Andalusian, Pura Raza Espanola, Lusitano, Gypsy Cob, Gypsy Vanner, Paint Horse, Quarter Horse (Avila et al., 2022). Not detected in that study in Appaloosa, Arabian, Connemara Pony, Dutch Warmblood, Hanoverian, Icelandic Horse, Knabstrupper, Miniature Horse, Missouri Fox Trotter, Morgan Horse, Mustang, Norwegian Fjord Horse, Oldenburg, Percheron, Pony of the Americas, Rocky Mountain Horse, Shetland Pony, Standardbred, Tennessee Walking Horse, Thoroughbred or Welsh Pony; absence in a sample does not prove absence in the breed.
      • Allele / carrier frequencies: allele frequency (Avila et al., 2022; 11,281 horses tested, 6,878 after removing close relatives): Andalusian 12% (n=135), Pura Raza Espanola 11% (n=80), Lusitano 6.4% (n=102), Gypsy Cob 1.7% (n=60), Gypsy Vanner 1.5% (n=67), Paint Horse 0.7% (n=1,019), Quarter Horse 0.03% (n=3,189). The authors note ascertainment bias, as samples were submitted for colour testing, so figures for less-sampled breeds may be overestimated.
      • Clinical / diagnostic notes for veterinarians: further recessive SLC45A2 dilutions: Sunshine, found in a Standardbred x Tennessee Walking Horse cross (Holl et al., 2019), and Snowdrop, found in a Gypsy horse (Bisbee et al., 2020).

      Key references:

      • Sevane N, Sanz CR, Dunner S (2019). Explicit evidence for a missense mutation in exon 4 of SLC45A2 gene causing the pearl coat dilution in horses. Anim Genet 50:275-278. doi:10.1111/age.12784. PMID 30968968.
      • Holl HM, Pflug KM, Yates KM, Hoefs-Martin K, Shepard C, Cook DG, Lafayette C, Brooks SA (2019). A candidate gene approach identifies variants in SLC45A2 that explain dilute phenotypes, pearl and sunshine, in compound heterozygote horses. Anim Genet 50:271-274. doi:10.1111/age.12790. PMID 31006892.
      • Bisbee D, Carpenter ML, Hoefs-Martin K, Brooks SA, Lafayette C (2020). Identification of a novel missense variant in SLC45A2 associated with dilute snowdrop phenotype in Gypsy horses. Anim Genet 51:342-343. doi:10.1111/age.12913. PMID 31961951.
      • 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.

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