LCORL (Size)

Description

Horses vary in size more than almost any other domestic species, from Miniature Horses under 34 inches at the withers to draft breeds standing over 18 hands. Body size is a complex trait influenced by many genes, as well as nutrition, health, and environment during growth. Even so, research has shown that a small number of genomic regions account for a large share of the size differences between horse breeds.

Across-breed studies have identified four major regions associated with body size in horses, on equine chromosomes 3, 6, 9, and 11. Together, these regions explain most of the variation in size between breeds. The region on chromosome 3, which contains the LCORL and NCAPG genes, is one of the most influential. This test examines a variant in that region.

LCORL and height

The LCORL/NCAPG region is associated with withers height both between breeds and within individual breeds. It has a similar role in other species: the same region influences body size and growth in cattle and is among the regions most consistently linked to height in humans.

Metzger et al. (2013) showed that the allele associated with greater height in horses is also associated with lower expression of the LCORL gene, pointing to LCORL as the likely gene behind the effect. The effect is roughly additive. Horses with two copies of the C allele (C/C) tend to be taller than horses with one copy (T/C), and horses without the C allele (T/T) tend to be smallest.

Why test for height?

Breeders can use this test to help select breeding stock toward a desired size, whether they aim to increase size in a sport or draft program or keep size down in pony and miniature breeding. Testing young horses can also give an early indication of their genetic size potential before they reach maturity, which is useful when planning a horse’s future discipline or marketing it.

Because height is influenced by many genes and non-genetic factors, this test indicates a genetic tendency rather than predicting a horse’s exact adult height. A T/T horse may still grow tall, and a C/C horse may not reach its potential without good nutrition and care. Results are most informative when considered alongside the size of the horse’s parents and relatives.

Possible results

Breeds Affected

All breeds

Reference

Expression levels of LCORL are associated with body size in horses.

Related Tests

• MSTN2 — SINE insertion — predicts optimal racing distance
• MSTN1 — SNP — the linked SNP marker for speed and distance
• Gait — ability to pace or trot at speed without breaking into a gallop

Testing performance traits? The Equine Trait Panel includes this test plus four others for $95.