RUNX1

A rearrangement (translocation) of genetic material involving the RUNX1 gene is found in approximately 7 percent of individuals with a form of blood cancer known as acute myeloid leukemia (AML). The translocation, written as t(8;21), combines genetic information from chromosome 21 and chromosome 8, fusing the RUNX1 gene on chromosome 21 with a gene on chromosome 8 called RUNX1T1 (also known as ETO). Because this genetic change affects CBF, the condition is classified as core binding factor AML (CBF-AML).

The resulting fusion protein, RUNX1-ETO, is able to form CBF and attach to DNA, like the normal RUNX1 protein; however, instead of turning genes on, it turns them off. This change in gene activity blocks the maturation (differentiation) of blood cells and leads to the production of abnormal, immature white blood cells called myeloid blasts. While t(8;21) is important for leukemia development, a mutation in one or more additional genes is typically needed for the myeloid blasts to develop into cancerous leukemia cells.

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Translocations and other types of mutations involving the RUNX1 gene have been associated with different types of leukemia and related blood disorders, including acute lymphoblastic leukemia (ALL), chronic myelomonocytic leukemia (CMML), familial platelet disorder with predisposition to acute myeloid leukemia, and myelodysplastic syndromes (MDS). Depending on the type of mutation, these conditions can be related to impaired regulation of gene activity or loss of normal gene function. The RUNX1 gene mutations associated with these diseases are somatic mutations and are not inherited. They are found only in certain cells of the body.