title: Preoperative use of platelets in a 6-year-old with acute appendicitis and a myosin heavy chain 9-related disorder: a case report and review of literature.
abstract: BACKGROUND
  Mutations of nonmuscle myosin heavy chain 9 (MYH9) gene are an autosomal dominant cause of inherited thrombocytopenia in children. MYH9 spectrum disorders include May-Hegglin anomaly and Sebastian, Fechtner, and Epstein syndromes. Patients with these disorders often present with macroplatelets and thrombocytopenia and have a mild bleeding tendency; extrahematologic manifestations (nephropathy, deafness, and cataracts) correlate with specific mutations. No definitive guidelines exist for preoperative prophylactic platelet (PLT) transfusion in these patients.
  
  
  METHODS
  This was a case study and literature review.
  
  
  RESULTS
  A 6-year-old male presented with appendicitis. Review of records revealed that he and his siblings had thrombocytopenia; polymerase chain reaction amplification with DNA sequence analysis showed a variation in the MYH9 gene previously reported as a known cause of MYH9-related disorders. Involvement of other organ systems was not found on initial work-up. The patient's PLT count on admission was 20 × 10(9) /L. The degree of thrombocytopenia prompted transfusion of apheresis PLTs and he had good response (73 × 10(9) /L). After infusion he developed hives, rash, itching, and nausea, which resolved after administration of epinephrine and hydrocortisone. Transfusion reaction work-up was negative and symptoms were interpreted as an allergic reaction. The appendectomy was uneventful.
  
  
  CONCLUSIONS
  This patient's PLT count was within guidelines to warrant transfusion; however, some patients with MYH9 mutations have counts above the transfusion threshold. To the authors' knowledge, there are no set guidelines for preoperative prophylaxis in a patient with an MYH9 deficiency. The management of the bleeding diathesis in these patients, especially in the setting of invasive procedures, is uncertain.
authors.affiliation: Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina.
authors.forename: Yekaterina
authors.initials: Y
authors.lastname: Eichel
authors.affiliation: Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina.
authors.forename: Lee Marie
authors.initials: LM
authors.lastname: Tormos
authors.affiliation: Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina.
authors.forename: Jerry E
authors.initials: JE
authors.lastname: Squires
mesh_terms: D000208:Acute Disease; D001064:Appendicitis / Q000097:blood / Q000601:surgery*; D002648:Child; D006319:Hearing Loss, Sensorineural / Q000097:blood / Q000235:genetics / Q000601:surgery*; D006801:Humans; D008297:Male; D020409:Molecular Motor Proteins / Q000235:genetics / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism; D017713:Platelet Transfusion; D011300:Preoperative Care; D013921:Thrombocytopenia / Q000097:blood / Q000151:congenital* / Q000235:genetics / Q000601:surgery
chemical_list: C103814:MYH9 protein, human; D020409:Molecular Motor Proteins; D018995:Myosin Heavy Chains