May-Hegglin anomaly

May-Hegglin anomaly is a hereditary blood disorder known as thrombocytopenia, a medical condition characterized by a reduced number of normal platelets, the presence of abnormally large platelets (macro-platelet) and cytoplasmic inclusions in white blood cells. As such, the disease shows no serious clinical symptoms, but it is important to diagnose it, as conditions such as thrombocytopenia and macro-thrombocytosis may be associated with clinically significant diseases. Thrombocytopenia is usually characterised by prolonged bleeding time and spontaneous bleeding in the skin, mucous membranes or organs. Leukocyte inclusions can then cause immune problems, manifested for example by skin lesions.

The disease is caused by a missense mutation c.5521G>A in the MYH9 gene. Inheritance of the mutation is autosomal dominant. This means that one copy of the mutated gene inherited from one of the parents is enough to cause the symptoms of the disease. The genetic test can clearly reveal the genotype of the animal and is a useful tool for breeders to prevent unintentional breeding of puppies with this disease.

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References:

Flatland, B., Fry, M.M., Baek, S.J., Bahn, J.H., LeBlanc, C.J., Dunlap, J.R., Carroll, R.C., Kosiba, D.J., Millsaps, D.J., Schleis, S.E. : May-Hegglin anomaly in a dog. Vet Clin Pathol 40:207-14, 2011. Pubmed reference: 21554370