Scientists often talk about cell fate and commitment in terms of mechanisms that control gene expression (transcription factors, chromatin remodeling, etc.). But by studying Diamond-Blackfan anemia (DBA), rare genetic blood disorder, a team led by researchers from the Broad Institute of MIT and Harvard and the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center (DF/BC) have found a surprising mechanism that controls whether red blood cells achieve full development, one that has nothing to do with expression.