Black, White, or Shades of Gray?

Learn details about five-panel genetic testing and its positive influence on breeding decisions.

- Barb Crabbe

IN THE LATE 1980s, A MYSTERIOUS DISEASE ROCKED the Quarter Horse world, as well as breeds crossed with Quarter Horses. Horses suffering muscle tremors, weakness, collapse, and even death made headlines when the cause was traced to a genetic disease attributed to a prominent Quarter Horse bloodline. When researchers announced that HYPP (hyperkalemic periodic paralysis) linked to one very famous stallion named Impressive, there was an uproar in breeding barns across the country.

A decade later breeders began to accept the importance of reducing the spread of this deadly disease. In 1998, the American Quarter Horse Association adopted a rule requiring all foals descending from Impressive to be tested for HYPP, with results listed on their registration papers. In 2007, horses carrying two genes for this disease were no longer accepted for registration. This marked the beginning of genetic testing and AQHA’s efforts to minimize the spread of genetic diseases within the breed.

Fast-forward to 2016. Genetic tests are now available for five different heritable diseases that’ve been identified in Quarter Horses and other stock breeds.

Here, I’ll explain what the five-panel genetic test is all about. First, I’ll give you a primer on basic genetics so you can understand how genes are inherited. Then, I’ll teach you the basics about the five different diseases that make up the five panel genetic test. With this information, you’ll better understand how testing can help you make informed breeding decisions.

Genetics 101

When egg and sperm get together to create a foal, there’s a lot going on behind the scenes. Size, color, temperament—even some aspects of health—are predetermined by the way traits passed from the mare and stallion combine. The science behind all of this is called genetics, and it’s a complex, fascinating process. Here’s how it works.