May-Hegglin anomaly is a genetic disorder characterized by thrombocytopenia, giant platelets, and leukocyte inclusions.
The main feature of May-Hegglin anomaly is the presence of Döhle body–like inclusions in some types of leukocytes or WBCs (White Blood Cells) such as neutrophils, eosinophils, and monocytes. Other common features are abnormally large and poorly granulated platelets and thrombocytopenia (low blood platelet count).
May-Hegglin anomaly is classified as a hereditary macrothrombocytopenia.
It is a genetic disease caused by mutations in MYH9, the gene encoding for the non-muscle myosin heavy chain-IIA (NMMHC-IIA). MYH9 gene is located on chromosome 22 (22q12-13).
It is a member of the MYH9-related diseases along with:
May-Hegglin anomaly is an inherited disease with an autosomal dominant pattern. It means that just one defective copy of the gene (from the father or the mother) is required for suffering the disease.
Approximately 50% of the patients do not have any symptoms. If symptoms are present, the most common one is abnormal bleeding tendency. For example:
Other less frequent symptoms of MYH9-related diseases include:
The diagnosis is based on the detection of inclusion bodies in WBCs, mainly in the neutrophils.
In general, no treatment is required in people affected by May-Hegglin anomaly and the disease is usually discovered incidentally.
In case of excessive bleeding, platelet transfusion is considered the best therapeutic option.