A paper published online on June 13 in the Journal of Experimental Medicine (www.jem.org) identifies new gene¹ mutations in patients with chronic³ lymphocytic leukemia（白血病） (CLL)—a disease often associated with lack of response to chemotherapy and poor overall survival. CLL is the most common leukemia in the Western world, but the disease varies greatly from patient to patient with regard to prognosis, survival, and disease course. In attempt to understand the genetic⁴ basis for this heterogeneity⁵（异质性） , a group led by Riccardo Dalla-Favera at Columbia University and Gianluca Gaidano at Amedeo Avogadro University of Eastern Piedmont, Novara, Italy surveyed the landscape of mutations in the genes⁶ of CLL patients. They found several mutations not previously⁷ linked with CLL, but most patients had relatively⁸ few genetic mutations compared to some other types of cancer.

The team then turned their attention to NOTCH1, a gene that controls cell division and survival and is often activated⁹ by mutation² in other types of leukemia. CLL patients harboring NOTCH1 mutations at the time of diagnosis¹⁰ had a significantly poorer prognosis and shorter survival than patients without NOTCH1 mutations. And NOTCH1 mutations were much more common in samples from patients whose disease progressed to more high-risk forms or who failed chemotherapy（化学疗法） treatment.

These findings point to the NOTCH1 pathway as potentially useful for diagnostic and therapeutic¹¹ purposes in human CLL.