Around 25% of patients with an ETV6 mutation develop an acute leukemia or MDS. The most frequent malignant disease of the blood formation system (hematological malignancy) is pre-B-ALL (acute lymphoid leukemia of the B-cell lineage), with a currently observed average age of incidence of 7 years (age range of 2-37 years). However, other hematological malignancies have been described as well, such as MDS, AML (acute myeloid leukemia), and chronic myelomonocytic leukemia (CMML).
In addition to diseases of the blood formation system, an ETV6 mutation is also associated with the occurrence of other malignant tumors. Early-onset colon cancer has been reported in a few patients, and a few cases of breast cancer, meningioma (a brain tumor), small intestinal cancer, and kidney cancer.
In addition to the increased risk of cancer, it is also common for mild to moderate thrombocytopenia to occur. There is not necessarily always a tendency to bleed, usually it is associated with mild to moderate bleeding episodes, and only rarely with a pronounced tendency to bleed. Typical symptoms include nose and/or gum bleeds, increased bruising, and prolonged menstrual periods. Thrombocytopenia and a tendency to bleed can already manifest during infancy.