Two SNPs in the SILV gene are associated with silver coat colour in ponies.

The research article discusses the study of the SILV gene in horses and its association with the silver coat color peculiar to certain breeds such as Shetland ponies and Icelandic horses. The researchers identified two specific mutations or SNPs (Single Nucleotide Polymorphisms) in the SILV gene that were completely associated with the silver phenotype.

Investigation of the SILV Gene

• The researchers decided to focus their study on the SILV gene because it is a known candidate gene for pigment dilution in various species.
• In order to scrutinize the SILV gene in horses, a 1559-bp genomic fragment of this gene was sequenced in 24 horses.
• During the sequencing, five SNPs or variations in the DNA sequence were identified.

Association of SNPs with Silver Phenotype

• Two out of the five SNPs detected (DQ665301:g.697A>T and DQ665301:g.1457C>T) were found to be completely associated with the silver phenotype. This silver phenotype is characterized by a chocolate-to-reddish body color with a white mane and tail.
• These two SNPs were then genotyped in a larger sample of 112 horses belonging to eight different color phenotypes.
• The scientists found out that all eumelanin-producing horses (blacks and bays) that had an atypical white mane and tail were carriers of the [g.697T; g.1457T] haplotype, which included the two SNPs in question.
• The silver haplotype and phenotype were only identified in Shetland ponies and Icelandic horses.

SILV Gene in Chestnut Horses

• Interestingly, horses without eumelanin (i.e., chestnuts) were also carriers of the [g.697T; g.1457T] haplotype, but these horses did not show the silver phenotype.
• The researchers suggest that the white or flaxen mane often found in chestnuts might be due to another mutation in the SILV gene or due to variations in other genes affecting coat color.

In conclusion, this research provides insights into the genetic basis of the silver coat color in horses. It identifies two specific mutations in the SILV gene that are completely associated with this particular phenotype, further elucidating the complex genetic mechanisms that drive the diversity of color phenotypes in horses.