A hematological example was the discovery of a somatic IGH–DUX4 gene fusion in a child with B cell acute lymphoblastic leukemia (GOS_0131) that, due to variable and repetitive sequences29, is rarely detected by SOC assays (that is, FISH, targeted RNA sequencing and copy number array)7,10. The gene discussed is DUX4; the disease is B-cell acute lymphoblastic leukemia.