Researchers at the Georgetown University School of Medicine have recentlyuncovered a genetic irregularity that causes cancer in some individuals. David Solomon, an M.D./Ph.D. student in the group of Dr. Todd Waldman, an associate professor of oncology at the Lombardi Comprehensive Cancer Center, found that a mutation of the STAG2 gene causes an abnormal number of chromosomes during cell division, which in turn causes cancer, as he published in the August 19 issue of Science magazine.

Solomon explains that the STAG2 gene encodes a protein subunit of the “cohesin complex” that holds together chromosomes before they are pulled apart during mitosis, or cell division. Abnormal STAG2 genes cause problems in how chromosomes are held together, and this results in a phenomenon called aneuploidy, where some cells have too many chromosomes and others have too few. Aneuploidy is a driving factor in creating carcinogenic tumors.

Why is this significant? “This is the first gene that has ever been proven to directly cause aneuploidy when mutated or inactivated in human cancers,” Solomon said. “Aneuploidy is one hallmark of cancer, [but] researchers in the past have not known the mechanism and why this happens in cancer cells.”

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