GATA1

The GATA1 gene provides instructions for making a protein that attaches (binds) to specific regions of DNA and helps control the activity of many other genes. On the basis of this action, the GATA1 protein is known as a transcription factor. The GATA1 protein is involved in the specialization (differentiation) of immature blood cells. To function properly, these immature cells must differentiate into specific types of mature blood cells. By binding to DNA and interacting with other proteins, the GATA1 protein regulates the growth and division (proliferation) of immature red blood cells and platelet-precursor cells (megakaryocytes) to facilitate their differentiation. Red blood cells help carry oxygen to various tissues throughout the body and platelets aid in blood clotting. The GATA1 protein is also important for the maturation of several types of white blood cells that help fight infection, including eosinophils, mast cells, and dendritic cells.

Two versions of the GATA1 protein are produced from the GATA1 gene: a regular length protein and a shorter version called GATA1s. The GATA1s protein lacks a specific region called the transactivation domain. Although the specific function of this region is unclear, researchers believe that it interacts with other proteins to modify GATA1 protein function.

dyserythropoietic anemia and thrombocytopenia - caused by mutations in the GATA1 gene

At least eight different mutations in the GATA1 gene have been found to cause dyserythropoietic anemia and thrombocytopenia. Most of these mutations change a single protein building block (amino acid) in the GATA1 protein. GATA1 gene mutations disrupt the protein's ability to bind with DNA or interact with other proteins. This impairment in the GATA1 protein's normal function leads to increased proliferation,decreased differentiation, and premature death of immature blood cells. Immature blood cells cannot perform the functions of specialized, mature blood cells. A lack of differentiation causes a shortage of red blood cells (anemia) and platelets involved in blood clotting (thrombocytopenia), which are characteristic features of dyserythropoietic anemia and thrombocytopenia.

cancers - increased risk from variations of the GATA1 gene

Some gene mutations can be acquired during a person's lifetime and are present only in certain cells. These mutations are called somatic mutations, and they are not inherited. Somatic mutations in the GATA1 gene increase the risk of developing a disease of blood-forming cells called transient myeloproliferative disorder (TMD). These mutations usually occur during fetal development, and the increased risk only applies to people who are born with an extra copy of chromosome 21 in each of their cells, a condition known as trisomy 21 or Down syndrome.

Approximately 10 percent of people with Down syndrome develop TMD, usually at birth or soon after. TMD is characterized by the accumulation of immature megakaryocyte precursor cells in the blood, liver, and bone marrow. In most cases, TMD causes no signs or symptoms and disappears within three to four months. However, approximately 20 percent of infants with TMD will have serious complications such as an enlarged liver (hepatomegaly), a buildup of scar tissue in the liver (hepatic fibrosis), excess fluid accumulation in the body before birth (hydrops fetalis), and heart failure.

It is estimated that 20 to 30 percent of children with TMD will later develop a cancer of the blood-forming cells called acute megakaryoblastic leukemia (AMKL). The somatic GATA1 gene mutations found in individuals with TMD or AMKL prevent the production of the normal length GATA1 protein and only allow production of the shorter version, GATA1s. It is unclear why somatic GATA1 gene mutations increase the risk of developing these bone marrow disorders in people with Down syndrome.