Ring chromosome in myeloid neoplasms is associated with complex karyotype and disease progression

Ring chromosome (RC) is a poorly understood genetic anomaly seen in myeloid neoplasms. This study aims to shed light on the clinical significance of this finding. We identified 96 cases of myeloid neoplasms with RC from 3 academic hospitals. Clinicopathologic features and overall (OS) and leukemia-free survival were reviewed and compared to cases of myeloid neoplasms lacking RC. We identified 59 acute myeloid leukemias (AML-RC) and 37 myelodysplastic syndromes (MDS-RC) with RC identified on routine karyotyping. Seventy-five percent of AML-RC and 97% of MDS-RC had complex (>3 independent cytogenetic abnormalities) karyotypes. The median OS of AML-RC with complex karyotype was significantly shorter than AML-RC patients with a non-complex (≤3 independent cytogenetic abnormalities) karyotype (P=.001), but similar to AML patients with complex karyotype lacking RC (P=not significant). Compared to complex-karyotype MDS lacking RC, MDS-RC patients had shorter leukemia-free survival (P=.016) and a trend for shorter OS (P=.10). RCs were sometimes lost after therapy or appeared during disease relapse, suggesting that they may be associated with genetic instability.