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Down Syndrome and Leukemia

Each year, about 6,000 children in the United States are born with Down syndrome, also known as trisomy 21, a condition where they have an extra copy of their 21st chromosome. The extra chromosome causes delays in their mental and physical development and makes them more susceptible to certain health issues, including problems with their heart, lungs, vision and hearing. It also makes them more likely to develop certain diseases, like childhood leukemia.

Is leukemia common in Down syndrome?

Leukemia is still considered rare in children with Down syndrome, but they are more likely to develop leukemia than other children. One large-scale 2021 study found that 2.8% of children  with Down syndrome had leukemia, compared with only 0.05% of other children. In particular, children with Down syndrome are 150 times more likely than other children to develop acute myelogenous leukemia, or AML, before age 5. The study also found that children with Down syndrome were more likely to develop acute lymphoblastic leukemia, or ALL, at any age. 

How is Down syndrome related to leukemia?

For many years, scientists didn’t know why so many more children with Down syndrome developed leukemia. But this year, researchers at the Linda Crnic Institute for Down Syndrome discovered that it could have something to do with their stem cells.

Stem cells are special cells that replicate themselves and can develop into different types of cells. What the researchers found is that children with Down syndrome are more likely to have clonal hematopoiesis (CH), a condition where blood stem cells develop a mutation and then continue to replicate, leading to a buildup of mutated blood cells.

Some people with CH can be healthy and have no symptoms. But in others, CH can lead to blood cancers, especially AML.

Prognosis and Treatment for Children with Down Syndrome and Leukemia

In particular, children with Down syndrome tend to develop a subtype of AML called acute megakaryocytic leukemia, or AMKL. This subtype is very rare among other children and can be very difficult to treat, but children with Down syndrome and AMKL typically respond well to treatment. It’s believed that the very mutation that makes children with Down syndrome more likely to develop AMKL actually makes their cancers more susceptible to treatment. 

All children with leukemia are treated with some combination of chemotherapy. However, children with Down syndrome tend to have more side effects from chemotherapy, so their doctors will adjust their treatment to reduce the toxicity while maintaining its effectiveness.

Overall, 80% of children with Down syndrome and leukemia will survive. A child’s survival depends on many factors, however, so it’s important for parents to discuss their individual child’s prognosis with their doctor.

The American Childhood Cancer Organization is the nation’s oldest and largest grassroots organization dedicated to childhood cancer. We shape policy, raise awareness, and offer educational resources to children with cancer, survivors, and their families. With your help, we can continue to provide our support free of charge. Donate now.

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