The Gray Platelet Syndrome (GPS) is a hereditary bleeding disorder associated with a defect in the production of alpha granules by megakaryocytes.


Chromosome location:

(1) 3p21 if autosomal recessive inheritance

(2) 9q34 (gene for GFI1B) for autosomal dominant inheritance


Clinical features:

(1) mild to moderate bleeding disorder

(2) progression to myelofibrosis

(3) variable splenomegaly


Laboratory findings:

(1) thrombocytopenia with platelets larger than normal (“macrothrombocytopenia”)

(2) Platelets have a grayish appearance on light microscopy.

(3) There is an absence of alpha-granules in platelets on electron microscopy.

(4) Serum vitamin B12 is elevated (Gunay-Aygun et al).


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