title: May-Hegglin anomaly in a dog.
abstract: An 8-year-old female spayed Pug dog was presented for evaluation of cutaneous lesions occurring secondary to immunosuppressive treatment of presumed immune-mediated thrombocytopenia. Abnormal hematologic findings included persistent thrombocytopenia, macrothrombocytes, and variably shaped, often fusiform, blue cytoplasmic inclusions in neutrophils. May-Hegglin anomaly (MHA) was suspected based on the morphologic appearance of platelets and neutrophils. Examination of cells by transmission electron microscopy revealed normal platelet ultrastructure; neutrophil inclusions had features similar to those reported for inclusions in human MHA. Neutrophil function was within normal limits based on flow cytometric analysis. Thrombelastography indicated a prolonged clotting time (r), and PlateletMapping showed a lack of response to 2 μM ADP compared with a moderate response in the control dog. Immunocytochemical staining of blood smears using 2 commercially available antibodies against MYH9 protein (nonmuscle myosin heavy chain II) yielded negative results. However, genomic DNA sequencing analysis of the dog's MYH9 gene identified a single point mutation, resulting in substitution of lysine for glutamine at the 1841 amino acid position; this mutation is identical to one identified in people with MHA. To our knowledge, this is the first report of an MYH9 mutation in the dog. MHA-associated macrothrombocytopenia may be mistaken for immune-mediated thrombocytopenia.
authors.affiliation: Department of Pathobiology, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996, USA. bflatlan@utk.edu
authors.forename: Bente
authors.initials: B
authors.lastname: Flatland
authors.forename: Michael M
authors.initials: MM
authors.lastname: Fry
authors.forename: Seung J
authors.initials: SJ
authors.lastname: Baek
authors.forename: Jae H
authors.initials: JH
authors.lastname: Bahn
authors.forename: Casey J
authors.initials: CJ
authors.lastname: LeBlanc
authors.forename: John R
authors.initials: JR
authors.lastname: Dunlap
authors.forename: Roger C
authors.initials: RC
authors.lastname: Carroll
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Kosiba
authors.forename: Doris J
authors.initials: DJ
authors.lastname: Millsaps
authors.forename: Stephanie E
authors.initials: SE
authors.lastname: Schleis
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000648:ultrastructure; D004283:Dog Diseases / Q000097:blood* / Q000235:genetics; D004285:Dogs; D005260:Female; D006319:Hearing Loss, Sensorineural; D046529:Microscopy, Electron, Transmission / Q000662:veterinary; D018995:Myosin Heavy Chains / Q000235:genetics; D017354:Point Mutation / Q000235:genetics; D013916:Thrombelastography / Q000662:veterinary; D013921:Thrombocytopenia / Q000097:blood / Q000235:genetics / Q000662:veterinary* / Q000151:congenital
chemical_list: D018995:Myosin Heavy Chains