Which of the following is a disorder with absent platelet glycoprotein Ib/IX/V and in which the patient has moderate thrombocytopenia, large platelets, and normal aggregometry with all agents except ristocetin?

a. von Willebrand disorder (VWD)
b. Bernard-Soulier syndrome
c. Glanzmann thrombasthenia
d. Dense granule deficiency

ANS: B
Patients with Bernard-Soulier syndrome have deficient glycoprotein Ib/IX/V receptors on their surface. This is inherited as an autosomal recessive disorder; heterozygotes are normal or near normal, but homozygotes have (usually) a low platelet count, prolonged bleeding time, and enlarged platelets. Aggregation is normal with all agonists except ristocetin.