People with Down syndrome are at increased risk of developing leukemia. Researchers from the University of Copenhagen and Stanford University explain why by identifying specific changes in blood cells.
The study ” Single-cell multi-omics map of human fetal blood in Down syndrome ” was published in Nature.
Down Syndrome and Leukemia
Worldwide, one in 700 children is born with Down syndrome. A syndrome in which the child has an extra copy of chromosome 21, resulting in 47 chromosomes instead of 46. This typically results in distinctive physical features and some level of learning disability.
But newborns with Down syndrome also tend to have high red blood cell counts and are 150 times more likely to develop leukemia as they grow up than children without the condition.
“Our study revealed that the extra chromosome 21 alters the way DNA is packaged inside cells. This difference affects the way certain genes are regulated and may contribute to the development of leukemia,” explains Rebecca Moller, one of the researchers at the University of Copenhagen behind the new study.
To more precisely understand the impact of the extra chromosome 21, researchers sequenced the genes of more than 1.1 million cells from fetuses with and without Down syndrome.
“Interestingly, the dysregulations are not uniform and vary depending on the cell type and its environment. We found, for example, that blood stem cells from individuals with Down syndrome show dysregulation of genes involved in the production of red blood cells, which explains the symptoms in newborns,” says Professor Ana Cvejic, senior lead scientist at the University of Copenhagen.
The researchers also identified another key difference in the blood stem cells of people with Down syndrome: a greater number of mitochondria.
While energy production is essential, too many mitochondria can damage a cell and its DNA by producing harmful molecules.
“These damaging molecules, called reactive oxygen species, are known to attack DNA, creating mutations that can lead to preleukemia and, ultimately, leukemia,” explains Dr. Andrew Marderstein, of Stanford University and the study’s first author.
The study findings highlight the importance of understanding the complex relationship between genetics and the cellular environment of blood cells in individuals with Down syndrome.
“This study is the largest of its kind and demonstrates that the environment and genetic makeup of cells are crucial to understanding how blood cells and leukemia develop. Understanding these mechanisms is essential to guide future research in stem cell biology and cancer,” says Professor Ana Cvejic, who emphasizes that these insights pave the way for a better understanding of disease development in Down syndrome.
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