ARCH Clinic

What is ARCH?

ARCH, or age-related clonal hematopoiesis, can be a precursor to MDS. In cases of ARCH, one of the blood stem cells (or hematopoietic cells) acquires a genetic mutation. When the blood stem cell multiplies, the mutation is passed down to more and more cells. “Clonal hematopoiesis,” then, means that blood cells are developing from stem cells that are clones of an original, mutant cell. ARCH, also known as CHIP (clonal hematopoiesis of indeterminate potential), is diagnosed when a patient has genetic mutations of a certain kind and number but no other signs of blood disease, such as a low blood count or abnormally-shaped cells.

Age-related clonal hematopoiesis is associated with an increased risk of myelodysplastic syndromes and other blood cancers, as well as an increased risk of heart disease. However, the vast majority of people with ARCH never develop blood cancer and enjoy good health.

Washington University Physicians at Siteman Cancer Center see patients with ARCH, or CHIP, in their clinic, where they can devise a plan for appropriate monitoring. Follow-up is important if you have ARCH as well as a low blood count.

How is ARCH related to MDS and leukemia?

The genetic mutations that occur in age-related clonal hematopoiesis are the same genetic mutations that occur in blood cancers such as MDS. Consequently, patients with ARCH have a higher-than-normal chance of coming down with one of these conditions.

More study is needed to determine if, how, and under what circumstances the mutations of ARCH become cancer. In the future, ARCH could help physicians predict which individuals will go on to develop myelodysplastic syndromes and acute myeloid leukemia. Those patients could then be treated with preventive care.

How often does ARCH turn into blood cancer?

ARCH is unlikely to become blood cancer. Only about 4% of patients with age-related clonal hematopoiesis will receive a cancer diagnosis. However, even though most patients with ARCH will not go on to develop MDS or acute myeloid leukemia, it is still important to study this condition in order to better understand how MDS and leukemia arise and to find preventive solutions.

What causes ARCH?

As its name implies, ARCH is strongly connected to advancing age. Genetic mutations become more likely as the body ages: the mutations found in ARCH simply may be the result of the normal aging process. 10% of 70-year-olds are thought to carry these mutations, though ARCH is only diagnosed when the number of mutant cells reaches a certain threshold.

Does ARCH cause any symptoms?

Age-related clonal hematopoiesis does not cause any symptoms. It merely indicates the presence of genetic mutations in the blood stem cells and suggests a higher-than-average risk for blood cancers and heart disease.

ARCH research at Siteman Cancer Center

Washington University Physicians at Siteman Cancer Center are engaged in a number of research projects investigating genetic mutations of the blood stem cells and the role of these mutations in the development of cancer. They hope to use the mutations present in ARCH to unlock strategies for preventing cancer in at-risk patients.