When considering the 69 cases designated as ABC or GCB by the gold standard method, the LIMD1-MYBL1 Index correctly classified 26 out of 32 ABC and 30 out of 37 GCB cases, resulting in 81% sensitivity, 89% specificity for ABC group and 81% sensitivity, 87% specificity for GCB group. The gene discussed is LIMD1; the disease is aneurysmal bone cyst.