New discovery links circular DNA by-products to childhood leukaemia relapse

A previously overlooked type of circular DNA may help explain why some children with leukaemia relapse, according to landmark research from the University of Leeds published in Nature.

The research builds on earlier work that linked leukaemia (a type of blood cancer) to excised signal circles (ESCs) - circular forms of DNA that are normally produced as a by-product when the body creates antibody genes.

The new paper reveals for the first time that these DNA fragments can persist in cancer cells and may drive relapse in patients with B-cell precursor acute lymphoblastic leukaemia (BCP-ALL).

Lead author Dr Joan Boyes from the University’s Faculty of Biological Sciences and Astbury Centre explained;

"It has been known for over 40 years that small circular chromosomes, known as ‘double minutes’, are present in many cancers in addition to normal chromosomes. A further type of circular DNA, known as ESCs, were thought to be lost soon after they form. But we discovered that ESCs replicate and persist, just like double minutes.”