A 30-year-old woman presents with recurrent mucosal bleeding, prolonged bleeding time, and a normal platelet count. Platelet aggregation studies show absent aggregation with ADP, collagen, epinephrine, and arachidonic acid, but normal aggregation with ristocetin. Which diagnosis is most consistent?

• A Bernard-Soulier syndrome (GPIb deficiency)
• B Glanzmann thrombasthenia (GPIIb/IIIa deficiency) ✓
• C Von Willebrand disease type 1
• D Aspirin-induced platelet dysfunction

Explanation

Glanzmann thrombasthenia is caused by deficiency or dysfunction of glycoprotein IIb/IIIa (integrin alphaIIb-beta3), the platelet receptor for fibrinogen and the final common pathway for platelet aggregation. Since aggregation requires fibrinogen bridging GPIIb/IIIa on adjacent platelets, deficiency abolishes aggregation with all physiological agonists (ADP, collagen, arachidonic acid, thrombin). Ristocetin-induced agglutination (which requires GPIb-vWF interaction only) is preserved. Bernard-Soulier syndrome shows absent ristocetin aggregation due to GPIb deficiency.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.