Bone Marrow Disorders

The Janus Kinase 2 gene, commonly called the JAK 2 gene, produces the JAK 2 protein. The gene provides essential information to cells that synthesize this protein.

The JAK 2 protein regulates cell division (proliferation) and cell growth. In the bone marrow, it moderates the production of red blood cells from hematopoietic stem cells. The production of the JAK 2 protein is the initiation point of the JAK/STAT signalling pathway initiation point, which regulates the embryo’s development and haematopoiesis, stem cell development, and several other processes. The bone marrow gradually either starts or stops producing blood cells.

JAK 2 Gene Mutation

Mutations of the JAK 2 gene are commonly associated with various disorders, a phenomenon extensively researched worldwide. Primarily, JAK 2 mutations cause bone marrow disorders and associated conditions characterized by the excessive production of blood cells. This disorder group is collectively called myeloproliferative neoplasms (MPNs). The JAK 2 gene mutation can cause excess red blood cells (RBC), white blood cells (WBC), or platelets, depending on the condition. A blood test can determine JAK 2 gene mutation. To determine the type of MPN and the severity of the condition, the patient may require additional tests such as a bone marrow biopsy. 

According to the World Health Organisation, all MPNs are blood cancer.

The JAK 2 – V617F Gene Mutation

The JAK 2-V617F mutation is this class’s most common and most researched genetic mutation. It is a somatic mutation, meaning that it is a mutation that occurs after birth and is not inherited. In this type of JAK -2 mutation, phenylalanine (an amino acid) replaces another amino acid, valine, as the building block of the JAK 2 protein at position 617. The destabilized protein loses auto-inhibition, the ability to regulate itself. With the JAK 2 protein constantly turned on, the signal to the bone marrow to stop producing blood cells is lost. A few people have tested positive for a different form of JAK 2 gene mutation in a location known as Exon 12.

Disorders Related to the JAK 2 Gene Mutation

Here are some of the diseases that are most commonly associated with the JAK 2 gene mutation:

· Essential Thrombocythemia: Nearly 50% of the people diagnosed with Essential Thrombocythemia (ET) or primary thrombocythemia have the JAK 2 – V617F mutation. People diagnosed with this disorder have an elevated platelet count. Platelets or megakaryocytes are responsible for the normal clotting of blood in case of any injury to a blood vessel. The genetic mutation causes the overproduction of platelets, in turn leading to a blood clotting disorder or thrombosis. ET is known to progress slowly, often diagnosed after age 50. In rare cases, though, it may affect children and people of younger age.

· Polycythaemia Vera and Myelofibrosis: Nearly 96% of the people with Polycythaemia Vera have the JAK 2 – V617F mutation. An additional 3% of the affected people have the Exon 12 mutation. Mutations to the JAK 2 gene result in the auto-regulatory function of the JAK 2 protein, relaying a constant signal to the bone marrow to produce megakaryocytes and red blood cells. The blood becomes thicker, and its ability to flow decreases, causing a decrease in its ability to carry oxygen to different body parts. This condition is polycythaemia vera (PV). Nearly 10-15% of people with this condition are diagnosed with Myelofibrosis. Along with causing excess production of blood cells, the mutation also causes the release of collagen, leading to a build-up of scar tissue in the bone marrow.

· Other conditions – JAK 2 gene mutations are associated with several other bone marrow disorders and blood cancers. Certain conditions caused by the V617F mutation can cause a blockage of the liver veins from the hepatic venules to the inferior vena cava. This gene mutation may also cause Chron’s disease, which is not a bone marrow disorder.

The JAK – 2 Mutation Test

The jak2 mutation test is also called the JAK2-HUMAN test, Janus kinase 2 test or tyrosine-protein kinase JAK 2 test. It is a blood test that is down by drawing blood from a vein in the forearm. The associated pain or discomfort is minimal. Extensive research on JAK inhibitors has shown what slows down the activity of the JAK 2 protein.

Read Also: An Important Diagnostic Tool for Liver Diseases

By kinza BUTT

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