May–Hegglin anomaly (MHA), is a rare

genetic disorder A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality. Although polygenic disorders ...

of the blood

platelets Platelets, also called thrombocytes (from Greek θρόμβος, "clot" and κύτος, "cell"), are a component of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping, thereby ini ...

that causes them to be abnormally large.

Presentation

In the leukocytes, the presence of very small rods (around 3 micrometers), or Döhle-like bodies can be seen in the

cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The ...

Pathogenesis

MHA is believed to be associated with the ''

MYH9 Myosin-9 also known as myosin, heavy chain 9, non-muscle or non-muscle myosin heavy chain IIa (NMMHC-IIA) is a protein which in humans is encoded by the ''MYH9'' gene. Non-muscle myosin IIA (NM IIA) is expressed in most cells and tissues where it ...

'' gene. The pathogenesis of the disorder had been unknown until recently, when

autosomal dominant In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...

mutations in the gene encoding non-muscle

myosin Myosins () are a superfamily of motor proteins best known for their roles in muscle contraction and in a wide range of other motility processes in eukaryotes. They are ATP-dependent and responsible for actin-based motility. The first myosin ...

heavy chain IIA (''MYH9'') were identified. Unique cytoplasmic

inclusion bodies Inclusion bodies are aggregates of specific types of protein found in neurons, a number of tissue cells including red blood cells, bacteria, viruses, and plants. Inclusion bodies of aggregations of multiple proteins are also found in muscle cells ...

are aggregates of nonmuscle myosin heavy chain IIA, and are only present in

granulocyte Granulocytes are cells in the innate immune system characterized by the presence of specific granules in their cytoplasm. Such granules distinguish them from the various agranulocytes. All myeloblastic granulocytes are polymorphonuclear. They ha ...

s. These ''May-Hegglin inclusions'' are large, basophilic, cytoplasmic inclusions resembling

Döhle bodies Döhle bodies are light blue-gray, oval, basophilic, leukocyte inclusions located in the peripheral cytoplasm of neutrophils. They measure 1-3 μm in diameter. Not much is known about their formation, but they are thought to be remnants of the ...

in the granulocytes. It is not yet known why inclusion bodies are not present in platelets, monocytes, and lymphocytes, or how

giant platelet Giant platelet disorders, also known as macrothrombocytopenia, are rare disorders featuring abnormally large platelets, thrombocytopenia and a tendency to bleeding. Giant platelets cannot stick adequately to an injured blood vessel walls, resultin ...

s are formed. ''MYH9'' is also found to be responsible for several related disorders with macrothrombocytopenia and leukocyte inclusions, including Sebastian, Fechtner, and Epstein syndromes, which feature deafness, nephritis, and/or cataract. MHA is also a feature of the

Alport syndrome Alport syndrome is a genetic disorder affecting around 1 in 5,000-10,000 children, characterized by glomerulonephritis, end-stage kidney disease, and hearing loss. Alport syndrome can also affect the eyes, though the changes do not usually affect v ...

(hereditary nephritis with sensorineural hearing loss).

Diagnosis

Treatment

May-Hegglin Anomaly can be treated by various methods: * Medication;Tranexamic Acid * Desmopressin Acetate * Platelet Transfusion will not work, because the affected platelets will overtake the new platelets.

History

MHA is named for German physician Richard May (January 7, 1863 – 1936) and Swiss physician Robert Hegglin.R. Hegglin. Über eine neue Form einer konstitutionellen Leukozytenanomalie, kombiniert mit Throbopathie. Schweizerische medizinische Wochenschrift, Basel, 1945, 75: 91-92. The disorder was first described by Richard May in 1909 and was subsequently described by Robert Hegglin in 1945.

References

External links

{{DEFAULTSORT:May-Hegglin anomaly Coagulopathies Cytoskeletal defects Rare diseases