Swiss researchers recently identified a gene that controls height in Shetland Ponies and other pony breeds.
A team from the University of Bern, Agroscope Swiss National Stud and Bern University of Applied Sciences, School of Agricultural, Forest and Food Sciences first determined that a major height-regulating gene is located on chromosome 6 by comparing 48 Shetland Ponies of various heights, then sequenced the entire genomes of two ponies at opposite ends of the size spectrum: One stood six hands, three inches (27 inches) at the withers and the other measured 10 hands, one inch (41 inches).
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After reviewing the combined data, the researchers concluded that a specific variant in a gene known as HMGA2 is an important regulator of height in Shetland Ponies. One copy of the mutant allele leads to height reduction of almost four inches. Ponies that carry two copies of the mutant allele on average are almost eight inches shorter than ponies that do not have the mutant allele.
The researchers found the mutant allele in Shetland Ponies and, less frequently, two other pony breeds, the German Riding Pony and the New Forest Pony. It has not been found in full-sized horses.
Reference: “A non-synonymous HMGA2 variant decreases height in Shetland Ponies and other small horses,” PLoS One, October 2015
This article first appeared in EQUUS issue #460, January 2016.