May-Hegglin anomaly / MHA (MYH9-related) - Pug

What does this test analyse?

This genetic test analyses the MYH9 c.5521G>A-variant in the Pug. The condition is known as May-Hegglin anomaly, MHA, MYH9-related macrothrombocytopenia or macrothrombocytopenia with leukocyte inclusions.

What does this condition mean?

MHA mainly affects platelets and white blood cells. Affected dogs can have low platelet counts with very large platelets and inclusions in neutrophils. This can be confused with immune-mediated thrombocytopenia. Bleeding problems are not always present, but the genetic result is important when interpreting blood tests, skin lesions, oral plaques or unexpectedly low platelet counts.

Inheritance and result

The trait is inherited as autosomal dominant. One copy of the variant causes the tested form of MHA. A dog with two copies also has a positive genetic result; interpretation should consider the dominant effect and clinical context.

Practical value of this test

This test has practical value for owners, breeders and veterinarians because MHA can resemble another condition on blood testing. The result helps clarify the inherited cause and supports breeding selection, risk management and medical follow-up.

• Supports breeding selection by clearly identifying positive dogs and lines.
• Helps manage the risk of passing on a dominant MYH9 variant in matings.
• Adds important context for low platelet counts, giant platelets or abnormal blood smears.
• Can reduce confusion with acquired thrombocytopenia because the hereditary cause becomes visible.

Result in brief

• Clear (G/G): the tested variant was not detected.
• Positive (G/A): one copy was detected; this causes the tested form of MHA.
• Positive with two copies (A/A): two copies were detected; this is a positive result for the MYH9 variant.