Research press release


Nature Genetics

Genetic origins of the Grey horse

芦毛馬は独特の色をしているが、その根底にある遺伝子変異が同定されたことを報告する研究論文が、Nature Genetics(電子版)に今週掲載される。


ウプサラ大学(スウェーデン)のL Anderssonらは、8品種の合計800頭を超える芦毛馬において、ウマ25番染色体上の領域に遺伝子多型が検出され、芦毛以外のウマからは検出されなかったことを明らかにした。そして、さらなるマッピングの結果、芦毛馬において、隣接する2個の遺伝子(STX17とNR4A3)の過剰発現を促進する4,600塩基対のDNAの重複を同定した。


The genetic mutation underlying the characteristic colour of ‘Grey’ horses has been identified, according to a study published online this week in Nature Genetics.

Grey horses are typically descended from Arabian ancestors, including the famous purebred Lipizzaner stallions that are trained for classical dressage, and have been selected by humans for their striking appearance. Grey horses are born with dark hair but gradually lose pigmentation. As their hair becomes white by the age of 6?8 years, they take on a gray appearance due to their black skin underneath.

Leif Andersson and colleagues show that variants in a region on horse chromosome 25 are present in more than 800 Grey horses from 8 different breeds, but not in non-Grey horses. Through further mapping they identify a duplication of 4,600 base-pairs of DNA that promotes the over-expression of two neighbouring genes, STX17 and NR4A3, in Grey horses.

It is not yet known if the over-expression of only one of the genes, or both, is responsible for the loss of hair pigmentation. The authors also point out that 70?80% of Grey horses older than 15 years have melanomas, which reduces their lifespan. They propose that the STX17/NR4A3 over-expression simultaneously promotes susceptibility to melanoma and loss of hair pigmentation through effects on the proliferation rate of pigment-containing cells in the skin and hair follicles.

doi: 10.1038/ng.185

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