From Atlanta, at a meeting of the American Society of Hematology
People with Down syndrome are at least 10 times as likely as people without it to develop leukemia. Scientists now report that a mutation in the JAK2 gene on chromosome 9 shows up in one-fifth of people who have Down syndrome and acute lymphoid leukemia (ALL), suggesting that the mutation accounts for some of this increased risk. It's the second mutation implicated in the Down-leukemia puzzle.
People with Down syndrome have an extra, or third, chromosome 21. This so-called trisomy causes the condition, and scientists have wondered whether it also predisposes to leukemia. But since most people with Down syndrome don't develop the blood cancer, researchers assumed there were other genes involved. Five years ago, researchers reported that one-fifth of people with Down syndrome who have acute myeloid leukemia have a mutation in a gene called GATA1 on the X chromosome.