Giant platelet disorders, also known as macrothrombocytopenia, are rare disorders featuring abnormally large

platelet Platelets, also called thrombocytes (from Greek θρόμβος, "clot" and κύτος, "cell"), are a component of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping, thereby i ...

thrombocytopenia Thrombocytopenia is a condition characterized by abnormally low levels of platelets, also known as thrombocytes, in the blood. It is the most common coagulation disorder among intensive care patients and is seen in a fifth of medical patients a ...

and a tendency to bleeding. Giant platelets cannot stick adequately to an injured blood vessel walls, resulting in abnormal bleeding when injured. Giant platelet disorder occurs for inherited diseases like

Bernard–Soulier syndrome Bernard–Soulier syndrome (BSS) is a rare autosomal recessive bleeding disorder that is caused by a deficiency of the '' glycoprotein Ib-IX-V complex'' (GPIb-IX-V), the receptor for von Willebrand factor. The incidence of BSS is estimated to be ...

gray platelet syndrome Gray platelet syndrome (GPS), or platelet alpha-granule deficiency, is a rare congenital autosomal recessive bleeding disorder caused by a reduction or absence of alpha-granules in blood platelets, and the release of proteins normally contained in ...

and

May–Hegglin anomaly May–Hegglin anomaly (MHA), is a rare genetic disorder of the blood platelets that causes them to be abnormally large. Presentation In the leukocytes, the presence of very small rods (around 3 micrometers), or Döhle-like bodies can be seen in ...

Signs and symptoms

Symptoms usually present from the period of birth to early childhood as: nose bleeds, bruising, and/or gum bleeding. Problems later in life may arise from anything that can cause internal bleeding such as: stomach ulcers, surgery, trauma, or menstruation. Abnormality of the abdomen,

nosebleeds A nosebleed, also known as epistaxis, is bleeding from the nose. Blood can flow down into the stomach, and cause nausea and vomiting. In more severe cases, blood may come out of both nostrils. Rarely, bleeding may be so significant that low bloo ...

heavy menstrual bleeding Heavy menstrual bleeding (HMB), previously known as menorrhagia or hypermenorrhea, is a menstrual period with excessively heavy flow. It is a type of abnormal uterine bleeding (AUB). Abnormal uterine bleeding can be caused by structural abnorma ...

purpura Purpura () is a condition of red or purple discolored spots on the skin that do not blanch on applying pressure. The spots are caused by bleeding underneath the skin secondary to platelet disorders, vascular disorders, coagulation disorders, ...

, too few platelets circulating in the blood, and prolonged bleeding time have also been listed as symptoms of various giant platelet disorders.

Genetics

Many of the further classifications of giant platelet disorder occur as a result of being genetically passed down through families as an autosomal recessive disorder, such as in Bernard-Soulier syndrome and gray platelet syndrome.

Diagnosis

People may be diagnosed after prolonged and/or recurring bleeding episodes. Children and adults may also be diagnosed after profuse bleeding after a trauma or tooth extraction. Ultimately, a laboratory diagnosis is usually required. This would utilize platelet aggregation studies and flow cytometry.

Classification

Giant platelet disorders can be further categorized: * caused by auto-immune disorders, for example

Immune thrombocytopenic purpura Immune thrombocytopenic purpura (ITP), also known as idiopathic thrombocytopenic purpura or immune thrombocytopenia, is a type of thrombocytopenic purpura defined as an isolated low platelet count with a normal bone marrow in the absence of othe ...

(ITP), and characterized by low platelet count, but high MPV (mean platelet volume). * Caused by

glycoprotein Glycoproteins are proteins which contain oligosaccharide chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glyco ...

abnormalities:

velocardiofacial syndrome DiGeorge syndrome, also known as 22q11.2 deletion syndrome, is a syndrome caused by a microdeletion on the long arm of chromosome 22. While the symptoms can vary, they often include congenital heart problems, specific facial features, frequent i ...

* Caused by

calpain A calpain (; , ) is a protein belonging to the family of calcium-dependent, non-lysosomal cysteine proteases ( proteolytic enzymes) expressed ubiquitously in mammals and many other organisms. Calpains constitute the C2 family of protease clan C ...

defect: Montreal platelet syndrome * Caused by alpha granules defect:

* Characterized by abnormal neutrophil inclusions:

Sebastian syndrome Sebastian may refer to: People * Sebastian (name), including a list of persons with the name Arts, entertainment, and media Films and television * ''Sebastian'' (1968 film), British spy film * ''Sebastian'' (1995 film), Swedish drama film ...

* With systemic manifestations: Hereditary macrothrombocytopenia with hearing loss,

Epstein syndrome Epstein syndrome is a rare genetic disease characterized by a mutation in the MYH9 gene in nonmuscle myosin. This disease affects the patient's renal system and can result in kidney failure. Epstein Syndrome was first discovered in 1972 when two ...

Fechtner syndrome Fechtner syndrome is a variant of Alport syndrome characterized by leukocyte inclusions, macrothrombocytopenia,cause by mutation in the MYH9 gene on chromosome 22q11 AbstractThis study reports a family comprising four generations in whom nephriti ...

* With no specific abnormalities: Mediterranean macrothrombocytopenia * Harris platelet syndrome

Treatment

There has been no general recommendation for treatment of patients with giant platelet disorders, as there are many different specific classifications to further categorize this disorder which each need differing treatments. Platelet transfusion is the main treatment for people presenting with bleeding symptoms. There have been experiments with DDAVP (1-deamino-8-arginine vasopressin) and splenectomy on people with giant platelet disorders with mixed results, making this type of treatment contentious.

References

External links

{{Medical resources , DiseasesDB = , ICD10 = {{ICD10, D, 69, 1, } , ICD9 = , ICDO = , OMIM = , MedlinePlus = , eMedicineSubj = , eMedicineTopic = , MeshID = Rare diseases Syndromes affecting blood Coagulopathies