5’UTR Variant in KIT Associated With White Spotting in Horses.

The research work focuses on associating a variant in the KIT gene with the occurrence of white spotting in horses. The study proposes that a single nucleotide variant likely alters the regulation of KIT, disrupting melanoblast migration and causing white spotting on a horse’s coat.

Introduction

• The study revolves around the KIT gene, which influences melanoblast migration (movement of pigment-producing cells) and pigmentation (coloration) in mammals.
• Prior to this study, more than 30 KIT variants associated with white spotting in horses were documented.

Finding

• The research reports an association of increased white spotting on a horse’s skin and coat with a variant in the 5’UTR of KIT, marked as rs1149701677: g.79,618,649A>C.
• Horses having at least one alternate allele displayed phenotypic characteristics similar to those observed in other KIT mutations, with clear borders around unpigmented regions on the body, face, and limbs.

Quantitative Measurement

• Through a quantitative measure of depigmentation, or loss of pigmentation, an average white score of 10.70 was observed in individuals possessing the rs1149701677 variation, in contrast to an average score of 2.23 in the homozygous reference group.

Significance of rs1149701677

• The rs1149701677 variant location has a cross-species conservation score of 3.4. This high score points to the potential regulatory importance of this site across various species.
• The study found Ensembl, the genome browser, predicted a “moderately impactful” functional effect for the rs1149701677 variant, implying a notable influence in genetic function.

Conclusion

• The researchers propose that this single nucleotide variant could likely modify the regulation of KIT. In turn, this may disrupt melanoblast migration, resulting in increased white spotting on the coat of the horse.
• Another possibility put forward in the study is that the rs1149701677 variant could be linked with another nearby variant with a yet-to-be-discovered functional impact.
• The research proposes to name this new allele (variant form of a gene) “Holiday White” or W35, in line with conventional nomenclature.