There are four hereditary platelet disorders you should know a few things about. They really aren’t that complicated – there are just a few key concepts to remember for each. Yes, they are rare – I know. But to the patient who has the disease, it doesn’t matter how rare it is! Plus, they’ve shown up on boards. Part 1. Crazy.

Bernard-Soulier syndrome
In this disorder, patients have an abnormality in glycoprotein 1b, a platelet membrane receptor that binds von Willebrand factor. This means that the platelets have a difficult time binding to the subendothelium when necessary. Patients with this disorder, as you might expect, have severe bleeding. Giant platelets are present on the blood smear (see above).

Glanzmann thrombasthenia
The platelets in this disorder have abnormal or deficient glycoprotein IIB-IIIa, a platelet membrane receptor which binds fibrinogen. This means that the platelets can’t bind to each other (aggregate). This causes severe bleeding, which makes sense. I remember the mechanism in this disorder because the name has “asthenia” in it, which means weak or lacking energy. These platelets are so out of it they can’t even bind to each other!

Gray platelet syndrome
These platelets lack alpha granules (and therefore look empty, or gray). There may also be giant platelets in this disorder (like in Bernard-Soulier). Bleeding is mild.

Delta granule deficiency
Platelets in this disorder, not surprisingly, lack delta granules. This can be an isolated disorder, or it may be part of a syndrome (like Chediak-Higashi).