The accumulation of copy number losses, including 1p, 6p/q, 10q, 14q, and 18p/q and, less frequently, 2p/q, 3p, 4p/q, 7p, 8p/q, and 9p, compatible with instability is restricted to NF2-mutated meningioma. The gene discussed is NF2; the disease is meningioma.