Sebastian syndrome with abnormal platelet response to ristocetin.
Sebastian syndrome is characterized by enlarged platelets and Döhle-like body leukocyte inclusions. This syndrome is an MYH-9-related disease, a group that also includes May-Hegglin anomaly and Fechtner syndrome. The differential diagnosis of the MYH-9 diseases requires ultrastructural studies. Certain in vitro aggregation responses may be abnormal in these conditions.



A 6-month-old boy presented with macrothrombocytopenia but no overt bleeding tendency. Giant platelets and Döhle-like body leukocyte inclusions were present in blood smears from both the patient and his mother. Electron microscopy confirmed ultrastructural features consistent with Sebastian syndrome. Platelet aggregation studies were normal except for an impaired response to the agonist ristocetin.



In this patient peripheral blood analyses and platelet aggregation studies revealed disease features shared with the Bernard-Soulier syndrome, but this syndrome was excluded by cellsurface glycoprotein analysis.
Redman
Rachel
R
Department of Pathology, University of Florida, Gainesville, FL 32610-0275, USA. shunsm@pathology.ufl.edu
Shunkwiler
Sara M
SM
Harris
Neil S
NS
Kedar
Amos
A
Clapp
William L
WL
D001606:Bernard-Soulier Syndrome / Q000175:diagnosis; D001792:Blood Platelets / Q000648:ultrastructure*; D002675:Child, Preschool; D003937:Diagnosis, Differential; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D010974:Platelet Aggregation / Q000187:drug effects*; D012310:Ristocetin / Q000494:pharmacology*; D013577:Syndrome; D013921:Thrombocytopenia / Q000151:congenital / Q000175:diagnosis* / Q000473:pathology
D012310:Ristocetin