May-Hegglin and MYH9

May-Hegglin anomaly is one of several related conditions caused by mutations in the MYH9 gene, causing low platelet counts, abnormally large platelets, and sometimes other features affecting hearing, kidneys or vision. These MYH9-related disorders form a spectrum of conditions with overlapping features but varying severity.

They're caused by mutations in the MYH9 gene, which produces a protein important for normal platelet formation and function in various other tissues, inherited in an autosomal dominant pattern. This means an affected parent has a 50% chance of passing the mutation to each child.

The core feature across this spectrum is low platelet counts with abnormally large platelets, which can cause easy bruising or bleeding, and depending on the specific subtype, additional features such as progressive hearing loss, kidney disease, or cataracts may develop over time. The specific combination and severity vary considerably between individuals and even within families.

The low platelet count can cause bleeding tendency, though this is often milder than the platelet count alone might suggest, and some subtypes carry a risk of progressive kidney disease or hearing loss needing ongoing monitoring. Regular follow-up helps catch and manage these various potential complications.

Yes, they're inherited genetic conditions, and genetic testing can confirm the diagnosis and specific subtype, which helps predict likely additional features and guide appropriate monitoring. Genetic counselling is recommended for affected families given the inheritance pattern.

There's no cure for the underlying genetic condition, but the low platelet count usually needs no specific treatment unless there's significant bleeding, and any additional features like hearing loss or kidney disease can be managed with appropriate specific treatment as they develop. Regular monitoring helps identify when specific intervention becomes necessary.

Diagnosis typically involves blood tests showing characteristically low platelet count with unusually large platelets on blood film examination, confirmed with genetic testing for the specific MYH9 mutation. Family history assessment and monitoring for additional features helps clarify the specific subtype present.

Regular monitoring typically includes periodic hearing tests, kidney function tests, and eye examinations, given the potential for these features to develop or progress over time in some subtypes. Your specialist will provide a personalised, lifelong monitoring schedule based on your specific subtype.

May-Hegglin anomaly is one specific presentation within the MYH9-related disorder spectrum, generally with milder additional features, while other names within this spectrum (such as Fechtner or Epstein syndrome) tend to have more prominent additional features like hearing loss or kidney disease. All result from mutations in the same MYH9 gene, and the specific presentation can vary even within the same family.

Unexplained low platelet counts with large platelets on blood testing should prompt haematology referral for further assessment and genetic testing. Private haematology consultations can typically be arranged within about two weeks, considerably faster than standard NHS waiting times.