Coat colour Silver / Silver dapple / MCOA (PMEL-related) - Horse

What does this test analyse?

This genetic test analyses the PMEL variant c.1849C>T, also known as the Z allele, Silver, Silver dapple or PMEL17/SILV. The variant dilutes black pigment in the coat and is also linked to Multiple Congenital Ocular Anomalies, or MCOA.

Silver is most visible in horses with black pigment. A black horse may become chocolate-coloured with silver-grey or almost white mane and tail. In bay horses, mainly the black points and long hairs are lightened. On a chestnut background the colour effect is often not visible, but the horse can still carry and pass on the variant.

Why is this test useful?

Silver is a coat-colour test with value beyond appearance. The same PMEL variant that creates the desired silver or silver dapple colour is also linked to MCOA. The result therefore supports both colour planning and deliberate breeding selection.

Practical value of this test

• Breeders can plan more accurately for silver, silver dapple, chocolate silver, bay silver or related colour expectations.
• Hidden carriers can be identified, especially in chestnut horses where silver may not be visible.
• The result helps explain why silver remains present in a line or appears unexpectedly in foals.
• For sale, registration and communication with buyers, a DNA result gives more certainty than appearance or pedigree alone.
• Because Z/Z horses have a higher chance of more severe MCOA features, the test helps breeders plan matings between Z carriers more deliberately.

Inheritance and result

The Z allele is autosomal dominant for coat colour and dosage-related for MCOA. N/N means that the tested variant was not detected. N/Z means that the horse carries silver and can pass the variant to about half of its offspring. Z/Z means that the horse carries two copies, will pass the variant to all offspring and deserves extra attention for MCOA-related eye features.