Less is known about these disorders because they are diagnosed so rarely. In fact, many have only been discovered in the last 40 years.
Rare clotting factor deficiencies
Rare clotting factor deficiencies are a group of inherited bleeding disorders caused by a problem with one or several clotting factors.
Clotting factors are proteins in the blood that control bleeding. Many different clotting factors work together in a series of chemical reactions to stop bleeding. This is called the clotting process.
Problems with factor VIII and factor IX are known as hemophilia A and B, respectively. Rare clotting factor deficiencies are bleeding disorders in which one of the other clotting factors (i.e. factors I, II, V, V + VIII, VII, X, XI, or XIII) is missing or not working properly.
Platelet Function Disorders
Inherited platelet disorders are conditions in which platelets don’t work the way they should even though there is a normal platelet count and this results in a tendency to bleed or bruise easily.
Platelets are small cells that circulate in the blood. They are involved in the formation of blood clots and the repair of damaged blood vessels. When a blood vessel is injured, platelets stick to the damaged area and spread along the surface to stop the bleeding (this process is called adhesion). At the same time, chemical signals are released from small sacks inside the platelets called granules (this process is called secretion). These chemicals attract other platelets to the site of injury and make them clump together to form what is called a platelet plug (this process is called aggregation).
With a platelet function disorder, the platelet plug does not form properly causing bleeding to continue for longer than normal. Platelet function disorders that can cause bleeding of different severities, include:
- Bernard-Soulier syndrome – This syndrome occurs when the platelets do not have the substance necessary to stick to the wall of the blood vessels.
- Glanzmann’s thrombasthenia – In this condition, the platelets do not have the protein needed to clump together.
- Platelet storage pool disorder – Platelets have storage pools to store substances that are released when a platlet plug needs to be created. This disorder exists when the platelets have faulty storage for these substances. This disorder is also called platelet secretion disorder.