Locus Information: SB locus

Inheritance: incomplete autosomal-dominant

→ Incomplete means, animals with only one copy of the variant (Sb1/n) will show a less pronounced phenotype than horses with two copies of the variant (Sb1/Sb1).

General Information:

  • White patches with indistinct borders (especially on head, belly and legs).
  • Horses with one copy of this variant (heterozygote) may be confused with the classic roan phenotype since they are very likely to display the roan coat and additionally extensive white on legs and head. Later is a good distinction to the classic roan phenotype.
  • Horses with two copies of the variant (homozygote) are usually completely white.
  • Breeds commonly displaying this phenotype are: Tennesse Walking Horse, Miniature Horse, Paint Horse, Azteca Horse, Missouri Foxtrotter, Shetland Pony, Spanish Mustang and Pony of the Americas.
  • Sb1 is the most abundant but not the only mutation causative for this pattern.
  • Sb1 is a special form of White Spotting/Dominant White.
  • If a horse shows a Sb1-like phenotype but does not have the respective mutation, it may be due to other mutations in the KIT gene (W-variants) or other yet unknown variations.

Possible Genotypes:

Genotype: Effects:
n/n No Sabino-1 mutation.
Sb1/n The horse has one copy of the Sb1-variant → pattern with indistinct white patches and/or white on head and legs. Phenotype is very variable.
Sb1/Sb1 The horse has two copies of the Sb1-variant → often completely white coat or only small remnants of color (often ears).

Testinformation: This test detects the change of a single basepair in the KIT gene.

Brooks, S.A., Bailey, E.: Exon skipping in the KIT gene causes a Sabino spotting pattern in horses. Mamm Genome 16(11):893-902, 2005. Doi: 10.1007/s00335-005-2472-y.

Further information is available at Online Mendelian Inheritance in Animals.

Blurred edges of patches are a distinct characteristic for the Sabino pattern.

Test #: H207
Samples: Blood, Hair
Price: 35 € (net)
Time required: 7-10 days

The roan phenotype and white face and legs are one kind of the Sabino pattern. Peculiarity is strongly variable.