MGA, a suppressor of MYC, is recurrently inactivated in high risk chronic lymphocytic leukemia

The genetic lesions identified to date in CLL do not fully explain the development of chemorefractoriness and RS transformation. Given the role of the MYC pathway in Richter syndrome, here we investigated high risk CLL for genetic alterations of the MAX gene associated (MGA) gene, a suppressor of MYC transcriptional activation. MGA mutations and deletions were restricted to a single allele in all evaluable cases and were not accompanied by alterations of the second allele. Collectively, by combining mutations and deletions, MGA disruption was observed in 5/48 (10.4%) high risk CLLs, including 3/19 (15.7%) fludarabine-refractory CLLs and 2/29 (6.8%) RS.This observation, along with the notion that MGA is a suppressor of MYC and an inhibitor of MYC-induced cell transformation [4], points to MGA disruption as a new genetic lesion affecting the MYC pathway in high risk CLL and corroborates the notion that activation of MYC is a major contributor to the pathogenesis of RS.