AQHA Adds MYHM Testing to Genetic Health Panel

AQHA Adds MYHM Testing to Genetic Health Panel

New genetic health online resources and testing for myosin-heavy chain myopathy help owners care for their American Quarter Horses.

roan horse mare herd in pasture (Credit: Baru Forell)

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Myosin-heavy chain myopathy is a genetic muscle disease that can result in two distinct clinic disease presentations that both involve muscle loss or damage and are linked to the same genetic variant. Screening for MYHM is now included in the American Quarter Horse Association’s genetic health panel. MYHM was added to the panel following a member-submitted rule-change proposal made to the AQHA Stud Book and Registration Committee. At the 2022 AQHA Convention, the Stud Book and Registration Committee approved the addition of MYHM to the genetic health panel, with the rule change forwarded to and approved by the AQHA Board of Directors.

Facts regarding the genetic health panel for MYHM,:

  • For horses tested through AQHA, MYHM will automatically be included in the results for tests ordered after December 1, 2022.

  • Breeding stallions tested after January 1, 2023, must have the complete panel, including MYHM, before offspring can be registered; stallions tested before January 1, 2023, who already have the 5-panel test results recorded with AQHA are not required to retroactively add MYHM.

  • Horse owners who want to add MYHM to existing health panel results have the option to add it to their horse’s record so long as the original hair sample is still available and viable for testing; the cost to add MYHM to existing panel results is being offered at a discounted rate of $20.

  • MYHM is being offered separately to add on to existing 5-panel results for a limited time. Once that limited-time offer expires, MYHM will only be offered in the full genetic health panel through AQHA.

  • To learn more about MYHM and other genetic mutations, refer to

  • If a horse is affected, consult with your veterinarian or other equine health care professional for managing your horse’s needs.

Learn more about MYHM at, a part of the new AQHA genetic health online resource.  

AQHA Genetic Health: New Online Resource

Along with testing for MYHM, the Association and AQHA Genetic Health Task Force have launched a new genetic health online resource available at

The new interactive tool educates owners and breeders about how genetic diseases affect an American Quarter Horse, providing information about special care the horse might require and prompting thoughtful breeding decisions. Genetic health panel results should be carefully considered when making thoughtful breeding decisions to prevent further issues to protect future generations of American Quarter Horses.

AQHA is fortunate to have a passionate group of members and scientists who care about the betterment of the American Quarter Horse who volunteer their time to serve on these committees and task forces and provide vital information for the decision-making process.

View the new genetic online resources at

For additional information on genetic testing, including requesting a test, access to forms and answers to frequently asked questions about DNA kits, genetic testing and parentage verification, visit

AQHA news and information is a service of the American Quarter Horse Association. For more news and information, follow @AQHA on Twitter and visit