Summary
Release of platelet dense granule contents occurs in response to vascular injury,
playing an important role in platelet aggregation and primary hemostasis. Abnormalities
of the platelet dense granules results in a bleeding disorder of variable severity
termed “storage pool defect” (SPD). We have examined the fawn-hooded hypertensive
(FHH) rat as a model of SPD in order to genetically map the locus (Bd) responsible for prolonged bleeding. Platelet function assays of the FHH rat confirmed
the presence of a platelet dense granule SPD. However electron microscopy and lysosomal
enzyme assays indicated differences between the FHH rat and other rodent models of
SPD. Genetic mapping through the use of congenic FHH rats localized the Bd locus to an approximately 1 cM region on rat chromosome 1. Through the use of comparative
mapping between species and analysis of the initial draft of the rat genome assembly,
six known and thirty-four putative genes were identified in the Bd locus. None of these genes have been previously implicated in platelet function.
Therefore positional cloning of the gene responsible for the bleeding disorder in
the FHH rat will lead to new insights in platelet physiology, with implications for
diagnosis and management of hemostatic and thrombotic disorders.
Keywords
Platelets - dense granules - storage pool defect - rats - genetic mapping