A variant form of thrombasthenia
M. D. Tarantino, J. J. Corrigan Jr, L. Glasser, C. M. Payne and M. A. Jeter
Department of Pediatrics, University of Arizona Health Sciences Center, Tucson.
We encountered two siblings with abnormal bruising since infancy. Studies
revealed functional platelet defects characterized by a lack of platelet
aggregation and adenosine triphosphate release on exposure to adenosine
diphosphate and collagen as well as variable responses with ristocetin (at
concentrations of less than or equal to 1.25 g/L) and arachidonic acid. In
addition, little or no platelet aggregation was observed after exposure to
hexadimethrine bromide (Polybrene), the calcium ionophore A23187, and the
thromboxane/endoperoxide analogue U46619. The membrane proteins IIIa and Ib
were present, as determined with monoclonal antibody testing, and no
platelet-associated IgG was found. Platelet analysis with routine electron
microscopy and ultrastructural cytochemistry revealed normal morphologic
features and no deficiencies in the number of alpha granules dense bodies
and other organelles. The platelet abnormality may represent a new variant
of thrombasthenia.