May-Hegglin Anomaly

 

Gene: MYH9

Transmission: Autosomal dominant (not confirmed)

For an autosomal dominant genetic disease, an animal must have at least one copy of the mutation in question to be at risk of developing the disease. Animals with two copies of the mutation generally have more severe symptoms and an earlier onset of the disease than animals with just one copy of the mutation. One or both of the parents of an animal with the mutation has one or two copies of the mutation. Animals that have one or two copies of the mutation can pass the mutation on to future generations.

Mutation: Simple substitution, MYH9 gene; c.5521 G>A, p.(E1841L), exon38

Medical system: Blood

Breeds: Carlin Pinscher, Pug

Age of onset of symptoms: Anomaly should be present at birth

The May-Hegglin Anomaly that has been described in Pugs is a congenital condition that affects platelets, a type of blood cell involved in normal coagulation. Diagnosis can be made by blood microscopy and also by DNA testing. Affected dogs have platelet abnormalities including large thrombocytes (macrothrombocytes) and reduced numbers of thrombocytes (thrombocytopenia) as well as abnormal inclusions within neutrophils. Affected animals do not generally show clinical signs and their bleeding time is normal. It is important to differentiate this condition from certain infectious diseases that can also produce macrothrombocytes and thrombocytopenia. In addition, some analytical instruments in diagnostic hematology laboratories may count macrothrombocytes as red blood cells, which can give abnormal hematological results.

A recent survey for this mutation involving over 5000 pugs revealed no animals that carried the mutation (Donner 2023).  This would suggest that this mutation and this genetic disease, although of academic interest, is of little clinical relevance.

 

References:

OMIA link: [1608-9615]

Donner J, Freyer J, Davison S, et al. (2023) Genetic prevalence and clinical relevance of canine Mendelian disease variants in over one million dogs.  PLoS Genet. 19(2):e1010651. [pubmed/36848397]

Flatland B, Fry MM, Baek SJ, Bahn JH et al. (2011) May-Hegglin anomaly in a dog. Vet Clin Pathol 40(2):207-214. [pubmed/21554370]