Concomitant deletion of the short arm (Del 1p13.3) and amplification or gain (1q21) of chromosome 1 by fluorescence in situ hybridization are associated with a poor clinical outcome in multiple myeloma.

The PFS and OS of patients with combined abnormalities of del (1p13.3)/1q21gain or amp was significantly worse compared to del(1p13.3) alone and 1q21gain or 1q21 amp alone, which identifies a subset of patients with poor clinical outcomes.