Backwards DNA Associated with Lukemia

When otherwise normal DNA adopts an unusual shape called Z-DNA, it can lead to the kind of genetic instability associated with cancers such as leukemia and lymphoma, according to a study by researchers at The University of Texas M. D. Anderson Cancer Center.

Interestingly, these sequences prone to forming Z-DNA are often found in genetic “hot spots,” areas of DNA known to be prone to the genetic rearrangements associated with cancer. About 90 percent of patients with Burkitt’s lymphoma, for example, have DNA breaks that map to regions with the potential to form these odd DNA structures.

Imagine untwisting the DNA ladder and then winding it up the other way. The result is a twisted mess with segments jutting out left and right, and the all important base pairs that hold the DNA code zigzagging in a jagged zipper shape. Scientists call this left-hand twist Z-DNA. This is a far cry from the graceful right-hand twisted helix that has become an iconic symbol of biology.

Analysis of the genome reveals that DNA sequences prone to forming the Z-DNA structure occur in 0.25 percent of the genome.

Since formation of Z-DNA is naturally occurring and can exist in the genome, the scientists next want to understand why cells can sometimes process the structure without creating double-stranded breaks. They also want to know why certain places in the genome become “hot spots” for these breaks, while other seemingly similar areas do not.

M. D. Anderson Cancer Center - News Release - When Good DNA Goes Bad

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