title: MYH9 related platelet disorders - often unknown and misdiagnosed.
abstract: MYH9 related platelet disorders are a relatively rare cause of thrombocytopenia. Located on chromosome 22, the MYH9 gene encodes the motorprotein non-muscular myosin heavy chain IIA (NMMHCIIA). Heterozygous defects in this gene lead to 4 different autosomal dominant syndromes namely May-Hegglin anomaly, Epstein syndrome, Fechtner syndrome and Sebastian platelet syndrome. All 4 syndromes are characterized by macrothrombocytopenia and a mild bleeding tendency. Depending on the position of the causative mutation within the gene, the risk increases for syndromic manifestations such as renal failure, hearing loss and pre-senile cataract. Mutations in the neck region of the NMMHCIIA protein are more likely associated with these comorbidities than mutations in the N- or C-terminal part of the gene. MYH9 related platelet disorders should be excluded in patients with chronic thrombocytopenia and large platelets. Most sensitive for diagnosis/exclusion are immunofluorescence studies using a blood smear. The biggest risk for these patients is ineffective but potentially harmful treatment based on the misdiagnosis of immune thrombocytopenia. This review provides a workflow for diagnosis and treatment of MYH9 related thrombocytopenia.
authors.affiliation: Institute for Immunology and Transfusion Medicine, Ernst-Moritz-Arndt-University, Greifswald, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Althaus
authors.forename: J
authors.initials: J
authors.lastname: Najm
authors.forename: A
authors.initials: A
authors.lastname: Greinacher
mesh_terms: D001792:Blood Platelets / Q000473:pathology; D002648:Child; D002892:Chromosomes, Human, Pair 22 / Q000235:genetics; D004252:DNA Mutational Analysis; D003937:Diagnosis, Differential; D005799:Genes, Dominant / Q000235:genetics; D006580:Genetic Carrier Screening; D006801:Humans; D008856:Microscopy, Fluorescence; D020409:Molecular Motor Proteins / Q000235:genetics*; D018995:Myosin Heavy Chains / Q000235:genetics*; D010375:Pedigree; D012985:Software Design; D013577:Syndrome; D013921:Thrombocytopenia / Q000175:diagnosis* / Q000235:genetics* / Q000473:pathology
chemical_list: C103814:MYH9 protein, human; D020409:Molecular Motor Proteins; D018995:Myosin Heavy Chains