May-Hegglin Anomaly is a rare, inherited, blood platelet disorder characterized by abnormally large and misshapen platelets (giant platelets) and defects of the white blood cells known as leukocytes. The defect of the white blood cells consists of the presence of very small (2-5 micrometers) rods, known as Dohle bodies, in the fluid portion of the cell (cytoplasm). Some people with this disorder may have no symptoms while others may have various bleeding abnormalities. In mild cases, treatment for May-Hegglin Anomaly is not usually necessary. In more severe cases, transfusions of blood platelets may be necessary.
In the past couple of years, it has become clear to physicians studying this disorder that May-Hegglin Anomaly is one of a family of five autosomal dominant, giant platelet disorders, each of which involves slight variants (alleles) of the same gene in the same location. The other giant platelet disorders related to May-Hegglin Anomaly are Sebastian Syndrome, Fechtner Syndrome, Epstein Syndrome, and the Alport-like Syndrome with macrothrombocytopenia. Advances in the understanding of one of these syndromes may help in understanding the others.
Some people with May-Hegglin Anomaly may have symptoms at birth while others may have no symptoms throughout their lifetime. Symptoms may include red or purple colored spots on the skin (purpura), nose bleeds (epitaxis), excessive bleeding from the mouth during dental work, headaches, and/or muscle weakness on one side of the body due to bleeding within the brain (intracranial bleeding).
Excessive bleeding may occur in some people with May-Hegglin Anomaly when steroid drugs used to treat another disorder are discontinued.
May-Hegglin Anomaly is inherited as an autosomal dominant genetic trait. The gene involved has been mapped to Gene Map Locus 22q11.2, and the protein generated by the gene is known as MYH9.
Genetic diseases are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother. Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50% for each pregnancy regardless of the sex of the resulting child.
May-Hegglin Anomaly is a rare blood platelet disorder that affects males and females in equal numbers. It occurs more often in people of Greek or Italian descent than among others. As of about 10 years ago, only about 170 cases were reported in the literature.
The diagnosis of May-Hegglin Anomaly is made by specialized blood tests that reveal giant, oddly shaped platelets and characteristic cellular “inclusions” in certain white blood cells (leukocytes). There also might be fewer platelets than normal (mild thrombocytopenia). In severe rare cases, people with May-Hegglin Anomaly may require transfusions of platelets. People with Chediak-Higashi Syndrome, a form of Albinism, have cellular inclusions that are very similar to those of May-Hegglin Anomaly.
Pregnant women with May-Hegglin Anomaly may experience episodes of bleeding. Therefore, expectant mothers and their unborn children should be monitored for abnormal bleeding and/or hemorrhages.
May-Hegglin Anomaly generally does not require therapy in mild cases. Genetic counseling may be of benefit for affected individuals and their families. Other treatment is symptomatic and supportive.
Research on genetic disorders and their causes is ongoing. The National Institutes of Health (NIH) is sponsoring the Human Genome Project which is aimed at mapping every gene in the human body and learning why they sometimes malfunction. It is hoped that this new knowledge will lead to prevention and treatment of genetic and familial disorders in the future.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
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